Evolution of the Hubble Sequence in Hierarchical Models for Galaxy Formation

a r X i v :a s t r o -p h /9602085v 1 17 F e

b 1996

Mon.Not.R.Astron.Soc.000,000–000(0000)Printed 1February 2008

(MN L A T E X style ?le v1.3)

Evolution of the Hubble Sequence in Hierarchical Models

for Galaxy Formation

C.M.Baugh,S.Cole,C.S.Frenk.

Department of Physics,Science Laboratories,South Road,Durham DH13LE

1February 2008

ABSTRACT

We present a model for the broad morphological distinction between the disk and spheroidal components of galaxies.Elaborating on the hierarchical clustering scheme of galaxy formation proposed by Cole et al ,we assume that galaxies form stars quiescently in a disk until they are disrupted into a spheroidal con?guration by mergers.Bulges and spheroids may continue to accrete gas from their hot coronae,and so they may grow disks again.Thus,an individual galaxy may pass through various phases of disk or spheroid dominance during its lifetime.To distinguish between disks and spheroids we add one additional free parameter to the semianalytic model of Cole et al.which we ?x by requiring that the predicted morphological mix should match that observed locally.Assuming an ?=1,standard cold dark matter cosmology,we calculate formation and merging histories,and the evolution in colour,luminosity and morphology of the galaxy populations in di?erent environments.Our model predicts that the bulges of spirals were assembled before the spheroids of ellipticals and the spheroids of cluster ellipticals were assembled before those of ?eld ellipticals.About 50%of ellipticals,but only about 15%of spirals,have undergone a major merger during the redshift interval 0.0≤z ≤0.5.In spite of their violent formation history,elliptical galaxies turn out to have colour-magnitude diagrams with remarkably small scatter.Apart from a general blueing of the galaxy population with redshift,the colour-magnitude diagrams are remarkably similar at redshift z =0.5and at the present day.The morphological mix of galaxies that become rich cluster members at high redshift is dominated by spiral galaxies,due to the long timescale for galaxy mergers compared with the timescale for cluster assembly at high redshift.The assembly of low redshift clusters is slower,allowing more galaxy mergers to occur in the progenitor halos.As a result z =0rich clusters become E/S0dominated and we ?nd a “Butcher-Oemler”e?ect that becomes weaker for poorer groups at high redshift.The ?eld luminosity function of red galaxies shows little evolution out to z ?1and the reddest galaxies at these redshifts are as bright as their local counterparts.The blue luminosity function,on the other hand,evolves rapidly with redshift,increasing its characteristic luminosity and becoming steeper at the faint end.These trends are similar to those recently observed in the Canada-France Redshift Survey.Our calculations serve to demonstrate that a simple prescription for the distinction between disks and spheroids that is compatible with hierarchical clustering goes a long way towards explaining many of the systematic trends observed in the galaxy population.

Key words:Galaxies:evolution-galaxies:formation-galaxies.

1INTRODUCTION

The fundamental question of why some galaxies appear ?at-tened like disks while others are spheroidal remains a ma-jor unsolved problem in galaxy formation.Attempts have

been made in the past to present this problem as a ‘na-ture’versus ‘nurture’dichotomy:is the morphology of a galaxy imprinted in the initial conditions or does it result from environmental processes such as mergers and tidal in-teractions?Sandage et al.(1970)postulated that the de-

2 C.M.Baugh,S.Cole,C.S.Frenk

termining factor is the protogalactic angular momentum:a disk or a spheroidal con?guration would result,respectively, from the collapse of a rapidly rotating or of a slowly rotating gas cloud.Building upon the classic study of the kinematics of stars in our galaxy by Eggen,Lynden-Bell and Sandage (1962),Larson(1975)and Gott&Thaun(1976)proposed that the signi?cant parameter is the ratio of the star for-mation timescale to the free-fall timescale.If the former is shorter,dissipationless collapse would lead to a spheroidal system,while disks would form from the dissipational set-tling of a rotating gas cloud.The‘nurture’hypothesis was ?rst strongly advocated by Toomre(1977)who argued that galaxies form initially as disks and ellipticals form subse-quently through violent mergers of disks.

A simple distinction between‘nature’and‘nurture’is not easy to accommodate within modern cosmological theory.In hierarchical clustering models,initial conditions and environmental e?ects are closely linked together.Proto-galactic objects are‘born’with a range of angular momenta and characteristic timescales and these as well as their envi-ronment and merger rates depend on the initial conditions. From an observational point of view,it is also clear that galaxy morphology re?ects the interplay of various phenom-ena.Dressler’s(1980)morphology-density relation indicates that dynamical processes that depend on environment are a major in?uence on the?nal con?guration of a stellar sys-tem.The well known excess of blue galaxies in clusters at high redshift–the Butcher-Oemler e?ect(Butcher&Oem-ler1978,1984;Allington-Smith et al.1993)–suggests that the predominance of certain morphological types depends also on cosmic time.This impression seems to be supported by the recent HST images of clusters at redshifts z～0.5, which display an abnormally high proportion of late spiral and irregular types(Dressler et al.1994,Couch et al.1994, Moore et al.1995).

Mechanisms that may transform one morphological type into another have been proposed and investigated in the past two decades.These range from ram pressure strip-ping of spirals by a hot intracluster medium(Gunn&Gott 1972),to galaxy‘harassment’by impulsive encounters in clusters(Moore et al.1995).Galaxy mergers continue to be a favourite explanation for the origin of at least some bright ellipticals(Schweizer&Seitzer1992)and for the predomi-nance of ellipticals and S0’s in rich clusters.N-body simu-lations of merging disk galaxies do indeed produce merger remnants with density pro?les resembling those of ellipti-cals(eg Negroponte&White1983).Nevertheless,objec-tions have been raised against the view that the majority of ellipticals result from the merger of two or more stellar frag-ments.Perhaps the most powerful of these is the very small scatter measured in the colour-magnitude diagram of rich cluster ellipticals and S0’s.For example,Bower et al.(1992)?nd that the rms scatter in the colour of elliptical galaxies in the Coma cluster is onlyδ(U?V)<0m.04.On this basis they argue that the bulk of the stars in these galaxies are between8and12Gyr old and that the galaxies themselves must have been assembled at that time.

The origin of galaxy morphology is now beginning to be addressed with numerical simulations that model both gravitational dynamics and gas physics.Some studies have concentrated on achieving a detailed understanding of merg-ers and interactions(For a review see Barnes&Hernquist 1992;some of the results of numerical simulations that are relevant to this paper are discussed in Section2.2)while others attempt to follow the formation of galaxies in their proper cosmological context(eg.Katz,Hernquist&Wein-berg1992,Evrard,Summers&Davis199?,Navarro,Frenk &White1995and references therein.)Although interesting results have emerged from these studies,these are still early days in this area and a number of di?culties,particularly re-garding the behaviour of cooling gas and its transformation into stars,require further study.In addition,these simula-tions are expensive in computer time and so only a limited range of parameter space has been explored to date.

An alternative approach to studying galaxy formation is seminanalytic modelling.This has already proved to be a powerful technique(White&Frenk1991,Cole1991,Kau?-mann et al.1993,Lacey et al.1993,Cole et al.1994).This approach is based upon an extension of the Press-Schechter formalism(Press&Schechter1974;Bond et al.1991,Bower 1991)whereby a Monte-Carlo realisation of the hierarchical clustering process is used to follow the collapse and merger history of dark matter halos.The current level of under-standing of the dynamics of cooling gas,star formation, feedback of energy into prestellar gas and galaxy mergers is encoded into a few simple rules that allow the process of galaxy formation within dark matter halos to be calculated.

A wide range of parameters and cosmologies are accessible within such models(eg Cole et al.1994,Heyl et al.1995).

The semianalytic models have enjoyed a number of sig-ni?cant successes,providing explanations for the general fea-tures of the galaxy luminosity function,the slope and scat-ter of Tully-Fisher relation,the faint galaxy number counts, their redshift and colour distributions,etc.However,a num-ber of details remain unresolved.For example,in the original Cole et al.(1994)model,galaxies as red as many observed ellipticals were not formed.This problem turned out to be due to approximations in the Bruzual and Charlot(1993) stellar population synthesis models used by Cole et al.With the revised models of Charlot et al.(1995),the colour distri-butions are in much better agreement with observations(see Figure2of Frenk et al.1995).The strong feedback restrict-ing star formation in low circular velocity halos assumed by Cole et al.(1994)resulted in a relatively?at faint end slope for the luminosity function,but in spite of this,the mod-els still produce more dwarf galaxies than observed locally by Loveday et al.(1992).More recent determinations,how-ever,indicate that the faint end of the luminosity function is still uncertain(McGaugh1994)and the revised model of Cole et al.in fact agrees quite well with the CfA luminos-ity function of Marzke et al.(1994;see Figure3of Frenk et al.1995).The Tully-Fisher relation recovered by Cole et al.has a scatter and slope that matches those observed,but is o?set from the data.This problem can be traced back to an overproduction of galactic size dark halos in cold dark matter(CDM)cosmologies(Kau?mann et al.1993,Heyl et al.1995).

In this paper,we present an extension of the model of Cole et al.(1994)that allows the light of each galaxy to be split into a disk and a bulge component.The main aim of

Evolution of the Hubble Sequence3

this paper is to use this model in order to test the extent to which the distinction between disk and spheroidal systems may be accounted for by the simplest scheme compatible with hierarchical clustering.We shall assume(for the reasons given in Section2)that stars form initially in a disk and that bulges and spheroids are formed from violent mergers of such disks.We therefore ignore secondary dynamical processes such as dynamical friction or galaxy harassment in clusters. With such a simpli?ed scheme,we do not seek to account for the details of the morphological sequence,but merely to understand the basis of a broad morphological classi?cation based upon the bulge-to-disk luminosity ratio.

Our study extends earlier analyses by Kau?man et al.(1993)and Kau?mann(1995b,1995c)who also pro-posed a merger driven scheme for the production of galactic bulges,with morphological classi?cations based on bulge-to-disk ratios.They predicted the colours and morphological mix of galaxies in clusters as a function of absolute mag-nitude and examined the spiral or blue fraction and the colour-magnitude relation of galaxies in high-redshift clus-ters.Whilst the galaxy formation schemes of Kau?mann et al.(1993)and Cole et al.(1994)are similar in spirit,there are di?erences in detail in the way that the evolution of dark matter halos,star formation,feedback and galaxy mergers are treated.In addition,there are signi?cant di?erences in our schemes for bulge formation which we discuss in Sec-tion2.2.Finally,in this paper we concentrate on somewhat di?erent issues from those investigated by Kau?man et al.

A brief outline of the galaxy formation scheme of Cole et al.(1994)is given in Section2.1.We describe the mecha-nism for bulge formation in Sections2.2and2.3.Some rep-resentative examples of galaxies with di?erent morphologies are given in Section3.We examine the systematics of bulge formation in Section4.The predictions of our model for the colours of galaxies as a function of type and environ-ment,the morphological mix in di?erent environments and the evolution of the luminosity function are compared with observations in Section5.Finally,we discuss the success and failings of our model in Section6.

A detailed comparison of the predictions of our model with the faint galaxy counts as a function of morphological type obtained by the Hubble Space Telescope Medium Deep Survey,is given in a separate paper(Baugh et al.1996).

2A MODEL FOR GALAXY FORMATION

2.1Galaxy Formation Scheme

In our semianalytic scheme,the complexities of galaxy for-mation are approximated by a set of simple rules which, wherever possible,are motivated by the results of numerical simulations.Full details of the basic scheme can be found in Cole et al.(1994).Below we give a brief outline of how the various relevant physical processes are incorporated into the model.

The collapse and merging of dark matter halos as a function of time are followed using the block model of Cole &Kaiser(1988)(see also Cole1991).This provides informa-tion about the distribution of halos as a function of mass,the redshift at which the halos collapse,the redshift at which they merge into bigger halos,and the properties of the halos into which subunits merge.Each dark matter halo has bary-onic material associated with it.When the halo forms,the associated gas is shock heated and attains the virial temper-ature of the halo.Over the lifetime of the halo,de?ned as the time interval between the formation of the halo and its merger with a larger halo or the redshift of interest,some fraction of this hot gas can cool,according to the standard cooling function for primordial abundances of helium and hydrogen.

Once the gas has cooled it can form stars.The star for-mation rate is assumed to be proportional to the mass of cold gas present divided by a star formation timescale.The latter is independent of the dynamical time at the epoch when the halo collapses,but is a function of the circular velocity of the dark matter halo.This is because the energy liberated by stellar winds and supernovae reheats some of the gas, giving rise to a feedback loop involving cooling,star forma-tion and heating.The details of this feedback mechanism are based upon the results of‘smooth particle hydrodynamics’simulations by Navarro&White(1993)and has a stronger dependence on halo circular velocity than is predicted by a simple binding energy argument(White&Rees1978,White &Frenk1991).Without feedback,the majority of gas in the universe would cool at high redshift and form stars in low mass halos,precluding the possibility of star formation in more massive halos later on(White&Rees1978,White &Frenk1991,Cole1991,Lacey et al.1993).Our feedback prescription strongly inhibits the formation of stars in halos with low circular velocity.

When a dark matter halo merges into a larger object, its hot gaseous corona is stripped and the gas becomes as-sociated with the new halo.However,the cold gas and stars of the progenitor galaxies remain as separate entities until the galaxies themselves merge.When a new halo is formed, we compute a timescale for the merger of its galaxies,based upon a formula again motivated by numerical simulations (Navarro,Frenk&White1995).This has a dependence upon the mass ratio of the participant galaxies that is weaker than that suggested analytically from pure dynamical fric-tion considerations.If the galaxy merger timescale is shorter than the lifetime of the halo,the galaxies merge at the epoch at which the halo forms.The central galaxy in a halo accretes gas that cools from the merged corona and forms stars.The remaining satellite galaxies can only continue to form stars until their reservoirs of cold gas are exhausted.

Luminosities for the resulting galaxies are calculated using spectral energy distributions predicted by the stellar population synthesis models of Bruzual and Charlot(1993, 1995).We ignore the e?ects of chemical enrichment since only spectral energy distributions for solar metallicity are available at present.The synthesis model that we adopt is the revised Bruzual-Charlot model,kindly provided to us by Stephane Charlot.It uses di?erent tracks for the late stages of stellar evolution than the earlier version(see Charlot et al.1995).For a single burst of star formation with age10 Gyr,the revised models are redder by?(B?V)=+0.1and ?(B?K)=+0.35than the earlier models.Note that subtle di?erences in the choice of?lter in a given band and in the

4 C.M.Baugh,S.Cole,C.S.

Frenk

Figure 1.The correlation between bulge to disk ratio in the B band and Hubble T type.The Simien and de Vacouleurs data is for a sample of 96galaxies;the data from de Jong is for 86face on spirals.The de Jong data is for a 2D decomposition using exponential pro?les for the bulge and disk.The points have been given a small,random,horizontal displacement for clarity.The dotted lines are the 20and 80percentiles for the Simien &de Vacouleurs data;the dashed lines are the 20and 80percentiles for the de Jong data.The two solid lines show the cuts on bulge to disk ratio that we use in this paper to make a broad distinction between morphological classes.

type of star used to set the zero point of a magnitude scale can lead to di?erences of up to a tenth of a magnitude for a given burst age in a particular stellar population model.In this paper we use slightly di?erent ?lters to those employed by Cole et al.(1994),in order to obtain B ?V colours con-sistent with those derived by Charlot et al.(1995)from the same population models.

Throughout this paper,we shall use the parameters of the “?ducial model”of Cole et al.(1994).This is a CDM cosmology with ?=1,h =0.5,?b =0.06,where h de-notes the Hubble constant in units of 100km s ?1Mpc ?1.The amplitude of the power spectrum of mass ?uctuations is normalised to reproduce approximately the abundance of rich galaxy clusters by setting the rms mass ?uctuation in top hat spheres of radius 8h ?1Mpc,σ8=0.67(White et al.1993).This ?ducial models requires strong feedback to su-press star formation in dwarf galaxies and a moderate galaxy merger rate.

2.2Bulge Formation

In our extended galaxy formation scheme,all galaxies ini-tially form stars in a disk as hot virialised gas cools onto a collapsed dark matter halo.Thus we implicitly make the assumption that the timescale for star formation is longer than the collapse timescale of the gas.A disk con?guration is the natural outcome of the dissipative collapse of gas at constant angular momentum and is indeed the con?gura-tion seen in SPH simulations (Katz 1991,Summers,Davis &Evrard 1993,Navarro,Frenk &White 1995.)

Spheroidal distributions of stars and galactic bulges can only form as the outcome of merger events.In a violent merger,which we de?ne as a merger in which the central galaxy accretes satellite galaxies with a total mass greater than some speci?ed fraction of its own mass,any cold gas that is present is turned into stars in an instantaneous burst.After the merger and burst of star formation,if any takes place,no further stars are added to the bulge,until the next major merger happens.Galaxies orbiting in a common halo may continue to form stars quiescently in a disk until their cold gas reservoir is exhausted.The central galaxy can also

Evolution of the Hubble Sequence

5

form disk stars from hot gas that cools and is accreted from the hot corona.

This scheme for bulge formation is similar to that adopted by Kau?mann et al.(1993)and Kau?mann (1995b,c).However,as mentioned in Section 2.1,their galaxy formation model is di?erent in detail to ours.In par-ticular,Kau?mann et al.consider galaxy mergers that oc-cur over the lifetime of a halo as a series of binary mergers.Hence,an individual satellite must bring in enough mass by itself in order to satisfy the criterion for bulge formation.No account is taken of the cumulative e?ects of disk heating or thickening caused by the prior accretion of satellites that were too small on their own to cause a signi?cant change in the morphology of the central galaxy.In the scheme used in this paper,we simultaneously consider all satellites that will merge with the central galaxy over the lifetime of the halo.Hence,we classify more merger events as ‘violent’mergers leading to the formation of a bulge.Whilst neither imple-mentation of galaxy merging is fully accurate,the two ap-proaches are likely to bracket what happens in reality.

To determine whether a merger is classed as ‘violent’,we list the galaxies that will actually coalesce after the merger of their respective dark matter halos.The most massive galaxy is termed the central galaxy and the others are called its satellites.We compute the ratio of the sum of the mass of cold gas and stars in the accreted satellites to the mass of cold gas and stars in the central galaxy R =

acc .sat .

M cold gas +M stars

6 C.M.Baugh,S.Cole,C.S.Frenk

whether the scatter in Figure1is entirely observational or whether it re?ects the fact that there is not a unique corre-spondence between bulge-to-disk ratio and T-type.

Several studies in the literature have examined the mor-phological mix of local?eld galaxies.There is a relatively small scatter amongst di?erent estimates of the elliptical fraction,ranging from10%(in the Revised Shapley Ames Catalogue,Sandage&Tamman1981)to20%(in a sub-sample of bright galaxies drawn from the RC3catalogue by Buta et al.1994).The scatter in the spiral fraction is larger, around20%,re?ecting the di?culty of distinguishing be-tween spiral and S0galaxies,particularly at fainter magni-tudes on photographic plates(Dressler1980),when it be-comes hard to detect the disk component in the presence of a signi?cant bulge.A recent study,based on a large homoge-nous sample,assigned types to90%of galaxies brighter than b J=16.44in the Bright APM Galaxy Catalogue(Loveday 1995;Table10).Incorporating the irregular/peculiar galax-ies into the spiral class and scaling up the fractions in each type to account for unclassi?ed objects,the morphological mix in this catalogue is E/S0/S+Irr=13/20/67.

To?x the value of the parameter f bulge,we constructed mock catalogues from the output of our models,with the same magnitude limit as the Bright APM Galaxy Catalogue, taking into account any evolution in the galaxy properties. Kau?mann et al.classi?ed galaxies whose bulge component is less than40%of the total light as spirals,galaxies whose bulge component is60%or more of the total light as ellipti-cals and galaxies with intermediate bulge to total light ratios as S0’s.If we adopt these de?nitions,we obtain spiral frac-tions of45%and55%for f bulge=0.5and0.7respectively. Alternatively,if we allow the maximum size of a spiral bulge to be45%of the total light and the minimum bulge in an elliptical to be65%of the total light,we obtain a morpho-logical mix of E/S0/S of23.5/22.5/54.0for f bulge=0.5.We shall adopt these de?nitions and this value of f bulge through-out this paper.The corresponding cuts in bulge-to-disk ratio are plotted in Figure1as solid lines.Galaxies lying below the lower solid line are classed as spirals,galaxies above the upper solid line as ellipticals and galaxies in between as S0s. Although it is clear that with some?ne-tunning,we could achieve a higher spiral fraction,we do not feel that this is justi?ed given the large uncertainties surrounding morpho-logical classi?cation(Naim et al.1995)and the large scatter between bulge-to-disk ratio and T-type.

3REPRESENTATIVE EXAMPLES

In this Section we follow the histories of a representative selection of galaxies in our model.At each galaxy merger event,we have recorded properties of the progenitor galax-ies,such as their stellar mass,cold gas mass and luminosities in various bands.We plot the star formation history of se-lected galaxies in a tree-plot,analogous to the schematic merger history of a dark matter halo shown in Figure6of Lacey&Cole(1993).For this purpose we have traced the history of these galaxies back to progenitor galaxies with dark matter halos of mass5×1010h?1M⊙.

We have selected a representative range of galaxies to plot,the properties of which are listed in Table1.For each galaxy,we show the amount of stars and stars plus cold gas in separate panels as a function of redshift.The horizontal dashed lines mark the redshift at which a merger event took place in the history of an object.The width of the black shaded regions indicates the mass of stars or cold gas and stars that are present in a particular object.The mass in cold gas and stars of the?nal galaxy at redshift zero is given unit width on the x-axis.We know the amount of cold baryonic material in each fragment at a merger,and,for simplicity, we perform a linear interpolation in the tree-plots between masses at subsequent merger events(although the actual star formation rate is exponential).The mass of cold ma-terial increases between merger events as gas cools over the halo lifetime and stars are formed.Hence,in a merger event, the width of the black shaded region for a particular pro-genitor indicates the fraction of the?nal mass of material (cold gas and stars or just stars depending on the plot)in the galaxy that this fragment was responsible for bringing in.Termination of a shaded region at high redshift indicates that the galaxy formed at that redshift or was contained in-side a dark matter halo with mass below the resolution limit of the tree.

The syncronisation of merger events is an artefact of the way in which we incorporate galaxy mergers into the block model.As discussed in Section2.1,after the dark matter halos have merged,we calculate a timescale for the satellite galaxies to merge with the central galaxy of the new halo. Providing that this time is shorter than the lifetime of the halo,we allow the galaxies to merge at the epoch at which the halo is formed.In reality,these galaxy merger events would be spread out in time,after the redshift at which the new halo was formed.

If we consider the tree for the spiral galaxy with ID 48506,we see that few mergers occured above the mass res-olution of the tree.The bulge of this object was formed by the mergers at z=2and z=0.4.Both these mergers are minor mergers,so there was no burst of star formation,and the disk of the accreting galaxy would have been preserved. However,the accreted stars would be put into the bulge component of the central galaxy.

The SO tree(ID48588)shows similarly few merger events,though the amount of cold gas and stars in the pro-genitors is more evenly matched in the merger at z～0.3, which is probably a major merger.The bulge to total ratio given in Table1is measured in B-band luminosity,and so will underweight the bulge component relative to the disk. Hence an object that would appear to have a high bulge to total ratio in terms of stellar mass,would be expected to have a lower bulge to total ratio in terms of B-band lumi-nosity.

The tree plots for the ellipticals(IDs48764and48681) show many more merger events.In particular48764,which is the central galaxy in a rich cluster at redshift zero shows many more mergers at higher z than48681,which is in a lower circular velocity halo.

The spiral and S0trees look fairly similar.There are fewer merger events than in the history of an elliptical and the last signi?cant merger takes place between only two pro-genitors.

7

8 C.M.Baugh,S.Cole,C.S.Frenk

Evolution of the Hubble Sequence

9

Table 1.Representative Galaxies

ID

M ?(1011h ?1M ⊙)

L B (1010hL ⊙)

V gal (kms ?1)

B-K

bulge/total

Type

Figure 4.The distribution of the redshift of the last ma-jor merger event for bright ellipticals (solid lines)and spirals (dashed lines).The upper and lower panels show di?erential and cumulative distributions respectively for galaxies brighter than m B ?5log h =?18.There are 462ellipticals that satisfy this condition and 152spirals in our Monte-Carlo realization.The dis-tributions in the upper panel have been normalised to the total number of objects in each class.

4THE EPOCH OF BULGE FORMATION

In our model,the bulges of spiral and elliptical galaxies form by the same mechanism,violent mergers of galaxies.It is instructive therefore to examine whether or not there are any systematic di?erences between the bulges of galaxies of di?erent

morphological type and in di?erent environments.

Figure 4shows the distribution in redshift of the last

Figure 5.The distribution of the redshift of the last major merger for bright ?eld ellipticals (solid lines)and cluster ellipticals (dotted lines)in halos with circular velocity v c >1000kms ?1.The upper and lower panels show di?erential and cumulative distribu-tions respectively for galaxies brighter than m B ?5log h =?18.

major merger event for ellipticals (solid lines)and spirals (dotted lines).The average redshift of the last major merger for elliptical galaxies is ˉz =0.68,whilst for spirals it is ˉz =1.26.In an ?=1cosmology,this corresponds to a time di?erence of 2Gyr.Our model predicts that ～50%of bright ellipticals have had a major merger between 0.0≤z ≤0.5,in which time only 15%of spirals have su?ered a signi?cant merger.

In Figure 5,we compare the redshift of the last ma-jor merger for ellipticals in the ?eld and ellipticals found in

10 C.M.Baugh,S.Cole,C.S.

Frenk

Figure 6.The fraction of the stellar mass of a galaxy at z =0that was formed in bursts triggered by major mergers.Galaxies classi?ed as ellipticals at z =0on the basis their bulge-to-disk ratio and with absolute magnitudes m B ?5log h

halos with circular velocity,v c >1000kms ?1.Cluster ellip-ticals form their bulge component at a higher mean redshift,ˉz =0.94,than ?eld ellipticals.This is because evolution is ‘accelerated’in the high density cluster environment and so the collapse and merging of the dark matter halos that end up in the

cluster occurs at higher redshift than in the ?eld.

As Figures 4and 5illustrate,our model predicts that the bulges of spirals are assembled before the spheroids of ellipticals,and that the spheroids of cluster ellipticals are assembled before those of ?eld ellipticals.

We have also calculated the fraction of the ?nal stellar mass of elliptical galaxies that is formed in bursts of star for-mation triggered by major mergers throughout the history of the galaxy.Figure 6shows the distribution of the fraction of the ?nal stellar mass formed in burst events,split into redshift bins.The curves have been normalised by the total number of bursts and so the relative areas under the curves indicate the number of bursts that take place in each redshift bin.Every bright elliptical galaxy in our sample has experi-enced a major merger between redshifts 0

Figure 7.The number of fragments,brighter than L ?/10,that were involved in the last merger event of galaxies brighter than L ?today,plotted against the redshift at which the merger took place.The dotted lines show the 20and 80percentiles of the distribution of fragments,and the solid line shows the median.

Evolution of the Hubble Sequence11 and the higher fraction of cold gas available at high red-

shift.Our results are in accordance with recent detections of intermediate age populations in elliptical galaxies.The data suggest that～15%of the V-band light in ellipticals was formed in an episode of star formation approximately 5Gyr ago,long after the formation of the bulk of the stars (Freedman1992,Elston&Silva1992).

A question that is often posed in connection with the interpretation of faint galaxy counts is how many fragments are needed at high redshift to make up a typical galaxy today(Guiderdoni&

Rocca-Volmerange1988,Broadhurst et al.1992)?In Figure7we plot the number of fragments brighter than L?/10that participated in the last merger event of galaxies that are brighter than L?today,against the redshift at which the merger took place.Thus the fragments plotted are up to～2.5magnitudes fainter than the present-day galaxy.Most spirals and S0s contained only one or two such fragments at z<1,although a few were‘broken-up’into?ve or six fragments.By contrast,a signi?cant fraction of present-day ellipticals contained more than4fragments at z?0.5.These sorts of numbers are similar to those invoked by Guiderdoni&Rocca-Volmerange(1988)and Broadhurst et al.(1992)to account for the faint number counts.These ad hoc‘merging models’,however,require further assump-tions and are not directly comparable to our hierarchical clustering scheme.

5COMPARISON WITH OBSER V ATIONS

5.1Colour as a function of morphology,

environment and redshift

Since no quiescent star formation takes place in a bulge be-tween merger events,model galaxies with large bulge-to-disk ratios are redder than model galaxies with small bulge-to-disk ratios.In Figure8,we plot B?K and B?V colours for present-day galaxies brighter than B=?20,against their B-band bulge-to-disk ratios.Di?erent morphological types are represented with di?erent symbols.Also plotted is a compilation of B?V colours by Buta et al.(1994)for a sample of bright galaxies taken from the Third Reference Catalogue(RC3)(de Vaucouleurs et al.1991).Buta et al.?nd a good correlation between Hubble T-type and colour. Converting T-type into a bulge-to-disk ratio(using the?t of equation(5)of Simien and de Vaucouleurs1986),this corre-lation is shown as a solid line in the lower panel of Figure8, with the1σscatter indicated by the dotted lines.There is very good agreement between our model predictions and the observations,although some of our galaxies with bulge-to-disk ratios less than20%appear a little too red.This discrepancy,however,is just over a tenth of a magnitude in B?V,comparable to the uncertainty in colour arising from the details of the?lter choice and the template star used to set the zero point.

Figure9shows diagrams of B-V colour versus absolute B magnitude at redshifts z=0and z=0.5.As before, triangles denote elliptical galaxies,crosses S0s and circles spiral galaxies.The ellipticals are the reddest population and show a remarkably small spread in colour,an issue to Figure8.B-K and B-V colours as a function of bulge-to-disk ratio at the present day.Triangles represent ellipticals,crosses SOs and circles spiral galaxies.The solid line in the lower panel shows the mean B-V colour for a sample of bright galaxies drawn from the RC3catalogue by Buta et al.1994;the dotted lines indicate the1σscatter.Only galaxies brighter than B=?20are plotted.

which we return below.Their colour-magnitude relation is essentially?at,in apparent contradiction with the naive ex-pectation from hierarchical clustering models in which the largest objects typically form last.As pointed out by Cole et al.(1994),this is a remarkable success of these models. The scatter in colour amongst spirals is larger than amongst ellipticals,re?ecting the more extended periods of star for-mation in disks.S0s have intermediate colour properties. Other than a general reddening of the populations and a slightly larger scatter in the colours of spirals,there is little change in the appearance of the colour-magnitude diagrams at z=0.5and z=0.This is in spite of the fact that a large fraction of the present-day stellar populations are still to form at z=0.5.

Next,we examine the colours of bright galaxies as a function of environment.Figure10shows the mean colours of ellipticals(triangles)and spirals(squares)found in halos of a given circular velocity,at redshifts z=0and z=0.5. The error bars give the root mean square scatter about the mean.There is no signi?cant dependence of colour on halo

12 C.M.Baugh,S.Cole,C.S.Frenk

Table2.Elliptical galaxy colours:galaxies brighter than B=?19.

colour cluster ellipticals?eld ellipticals

B-V0.937(0.031)0.828(0.027)0.922(0.034)0.754(0.048)

B-K4.044(0.071)3.731(0.063)4.009(0.071)3.563(0.107)

U-V1.520(0.080)1.221(0.059)1.478(0.085)1.046(0.100)

Evolution of the Hubble Sequence

13

Figure 11.The colour-magnitude relation in di?erent envi-ronments.The upper panels shows elliptical (triangles)and S0galaxies (crosses)found in all environments.The lower panel shows only those galaxies found in halos with circular velocity v c >1000kms ?1.The solid lines show the median U ?V colour for the cluster ellipticals and the dotted lines show the rms scat-ter from our model.These lines are reproduced in both panels for comparison.

epoch of galaxies in clusters.A similar trend is seen in the observations,although the available data

are relatively poor (Larson,Tinsley and Caldwell 1981).Table 2gives the mean colours and rms scatter in brackets for the entire population and for the subset of cluster ellipticals at redshifts z =0and z =0.5.Only galaxies brighter than B =?19are in-cluded in this calculation,yielding a total of 210galaxies at z =0and 100at z =0.5.The cluster subsample comprises 45ellipticals at z =0and 13at z =0.5.

Figure 11reiterates the point made earlier regarding the small scatter in colour displayed by our model elliptical galaxies.This is particularly true of ellipticals in clusters,a result ?rst obtained by Kau?mann (1995c)using similar models.The root mean square scatter for cluster ellipticals shown by the dotted lines in Figure 11was calculated by the Median Absolute Di?erence technique used by Bower et al.(1992).The scatter we ?nd for cluster ellipticals is δ(U ?V )=0.074,compared with the observed value of δ(U ?V )=0.04for the Virgo and Coma clusters.The scat-

Figure 12.The cumulative distribution of objects as a function of bulge-to-total light ratio in the B band.The solid line shows the whole galaxy population and the dotted line the subset of galaxies found in clusters,ie in halos with circular velocity,v c >1000kms ?1.

ter in our model increases for V >?21.The observational data is taken from the cluster core,whereas our model gives the properties of all galaxies within the virial radius of the cluster.Hence,a slightly bigger scatter in the colour of the cluster ellipticals in our model is to be expected.Such uni-formity may seem surprising in a model in which the bulk of the stars form relatively recently and galaxy mergers are the primary mechanism for the formation of ellipticals.The explanation for this lies in the fact that most of the stars that end up in bright cluster ellipticals were made in smaller fragments at higher than average redshift.When these frag-ments merge,residual star formation can occur but,as dis-cussed in Section 4,this contributes only a relatively small fraction of the ?nal light.Mergers therefore mainly move galaxies along the luminosity direction,with little change in colour.

The scatter in the colours of cluster ellipticals is com-parable at z =0.5and z =0(cf.Figure 10).This,again,agrees surprisingly well with the observations of Standford et al.(1995)who ?nd a similar scatter in optical-IR colour in two Abell clusters at z =0.374and z =0.407to the scatter found by Bower et al.(1992)in Coma and Virgo.5.2

The morphological mix in clusters and groups as a function of redshift

The best known environmental in?uence on galaxy morphol-ogy is Dressler’s (1980)morphology-density relation.In its simplest form this is the statement that the fraction of el-lipticals and S0s in clusters increases rapidly with the mean

14 C.M.Baugh,S.Cole,C.S.

Frenk

Figure 13.The spiral fraction of galaxies in groups and clusters as a function of halo circular velocity.The symbols indicate the richness of the group,de?ned as the number of galaxies brighter than m B ?5log h =?18.Triangles show groups with 2-10mem-bers,squares with 10-20members and circles with more than 20members.The upper panel shows model predictions at z =0and the lower panel at z =0.5.

projected galaxy number density.More recently,Whitmore and Gilmore (1991)have argued that the fundamental rela-tion is one between morphological mix and distance from the cluster centre.Re-analysing Dressler’s (1980)cluster sample,they found that the elliptical fraction rises steeply within 0.5Mpc of the cluster centre and that the fraction of S0s ac-tually falls within 0.2Mpc.This suggests that the morpho-logical mix depends upon a global property of the cluster rather than on a local property such as substructure.

Since our models contain no information on the spa-tial distribution of galaxies within clusters,they do not ad-dress Dressler’s morphology-density relation directly.The do,however,predict the morphological mix within the virial radius of a cluster (de?ned as the radius within which the mean density is 178times the mean background density.)For a 1015h ?1M ⊙halo that collapses at the present day,this radius is 1.6h ?1Mpc.Examination of Figure 1of

Whit-

Figure 14.As Figure 13but with the group richness de?ned as the number of galaxies brighter than m B ?5log h =?19.

more (1990)shows that the elliptical fraction at this radius is <20%,compared with a peak value of 60%at the cen-tre of the cluster.In Figure 12we compare the cumulative distributions of bulge-to-disk ratios for the galaxy popula-tion as a whole (solid line)with that for galaxies located in high circular velocity halos (v c >1000kms ?1)(dotted line).The cluster distribution is biased towards higher bulge-to-disk ratios,implying a morphology-density relation in the same direction as the observations.In rich clusters,22%of our model galaxies are ellipticals,compared to 12%in the population as a whole.

We investigate the dependence of morphology on envi-ronment further by plotting the spiral fraction as a function of the circular velocity of the halo to which the galaxies be-long.This fraction is shown in Figures 13and 14for galaxies brighter than M B ?5log h =?18and ?19respectively and spans the range of circular velocities from poor groups to rich clusters.To obtain these data,we constructed six reali-sations of the density ?uctuation ?eld,three sampled from a Gaussian distribution in the usual way and three more con-strained to be overdense,with amplitude distributed uni-formly in units of the rms ?uctuation on the scale of the

Evolution of the Hubble Sequence15 block.The scatter in the spiral fractions displayed in Fig-

ures13and14is large for poor groups and decreases for

higher v c clusters.In agreement with the results of Kau?-

mann(1995b),we?nd that the richest clusters are E/S0

dominated.

We can compare the model predictions of Figures13

and14with the data obtained by Nolthenius(1993)for

groups identi?ed in the CfA1redshift survey.We con-

vert circular velocities to velocity dispersions assuming an

isothermal potential and an isotropic velocity distribution,

√

σ1D=v c/

16 C.M.Baugh,S.Cole,C.S.Frenk

not signi?cant and do not a?ect our conclusions presented below.The SED can change rapidly in the range of wave-lengths measured by the U?lter,being especially sensitive to assumptions made about star formation and the choice of U?lter can lead to di?erences in the colour.

Using a larger mock catalogue,containing10000galax-ies,we compute the luminosity function of the red and blue galaxies in redshift bins,using the1/V max formal-ism employed by Lilly et al.(1995).The luminosity func-tions are plotted in Figure16,which may be compared di-rectly with Figure3of Lilly et al.(1995).The red galax-ies are shown in the left column and the blue galaxies in the right coloumn.Redshift increases down the plot.The dashed line is the Schechter function?t given by Loveday et al.(1992),with parameters scaled to AB magnitudes and H0=50kms?1Mpc?1,and is intended as a reference point. The open points with errorbars are the best?t luminosity function from Lilly et al.(1995).The?lled points show the predictions of our model.

The model luminosity function of the blue galaxies does show more evolution than that of the red galaxies,with the luminosity function steepening,particularly between the 0.05

Schade et al.(1995,1996)have analysed the morphol-ogy of the galaxies in one of the CFRS?elds.Though the main e?ect responsible for the evolution of the blue lumi-nosity function is the increase in the number or brightness of blue disk galaxies with increasing redshift,a population of CFRS objects that are bulge dominated but which have blue colours appears at high redshift.At z>0.5,Schade et al.(1996)?nd that～14%of the sample,roughly double the fraction for z<0.5.are“blue-nucleated galaxies”or BNG. With correction factors,this?gure is doubled and matches the fraction of BNGs in a smaller sample measured with the HST.In our mock catalogue,we can apply a similar crite-rion,identifying BNG’s as galaxies that have a rest frame colour bluer than(U?V)AB=1.6and a bulge to total lu-minosity ratio greater than50%.We?nd that5%of the our mock CFRS sample would be classed as a BNG at redshifts z<0.5,and this?gure rises to22%for z>0.5.

6DISCUSSION

We have presented an extension of the semianalytic galaxy formation scheme of Cole et al.(1994)that allows the light of a galaxy to be split into bulge and disk components.Galax-ies are assumed to form stars quiescently in a disk until a merger disrupts them into a spheroidal con?guration.Vio-lent mergers are accompanied by a burst of star formation that adds further stars to the bulge.After a major merger, a spheroid may accrete gas from its hot corona and grow a new disk.Thus,in this scheme,a galaxy may acquire a range of Hubble types during its lifetime.We have presented tree-diagrams that illustrate the growth of galaxies of di?erent types.

To distinguish between disks and spheroids requires adding one additional parameter to the semianalytic model: the relative mass of a satellite capable of disrupting a disk. We?x this,as well as the bulge-to-disk ratios that de?ne di?erent morphological types,by comparing the predicted morphological mix with that observed locally.Although for reasons of clarity we have used the words spiral and ellipti-cal to refer to di?erent classes,our simple scheme can only distinguish between broad morphological properties based upon whether the bulge or the disk makes the dominant contribution to the total light of the galaxy.We used this scheme within the‘?ducial’?=1,standard cold dark mat-ter model of Cole et al.in order to calculate the formation histories of galaxies with di?erent morphologies;the colours of galaxies of di?erent types at low and high redshift,and in?eld and cluster environments;the variation of morpho-logical mix with environment and the evolution of the lu-minosity function of red and blue galaxies as a function of redshift.

We?nd that most spirals and S0s had only one or two progenitors with luminosity greater than L?/10at redshift z<1,whereas a signi?cant fraction of ellipticals had?ve or six such progenitors.The average redshift of the last major merger undergone by present day spirals isˉz=1.26and by present day ellipticals isˉz=0.68.Our model predicts that the bulges of spirals were assembled before the spheroids of ellipticals and the spheroids of cluster ellipticals were as-sembled before those of?eld ellipticals.About50%of el-lipticals,but only about15%of spirals,have undergone a major merger during the redshift interval0.0≤z≤0.5.

Since major mergers are accompanied by a burst of star formation,we?nd that about half the population of bright ellipticals has undergone a burst of star formation in the past6-9Gyr.Such bursts account for around15%of the stellar mass of the galaxy at z=0and may be responsible for the‘intermediate age populations’detected in ellipticals by Rose&Tripicco(1986),Freedman(1992)and Elston& Silva(1992).They may also account for the observations of Barger et al.(1995)that suggest that～30%of the ellipticals in three clusters at z～0.3have experienced a burst of star formation in the2Gyr preceeding observation.Similarly, some of the‘E+A’spectra measured by Dressler&Gunn (1992)in cluster ellipticals may be the result of these merger-induced starbursts.

A striking result of our analysis,previously noted by Kau?mann(1995c),is the?at slope and small scatter in the colour-magnitude diagrams of cluster elliptical galax-ies(see also Cole et al.1994).This is a counter-intuitive outcome of hierarchical clustering where we might have ex-pected brighter galaxies to be bluer and a large scatter in colour due to the chaotic nature of mergers.In fact,the scatter we?nd amongst bright galaxies is comparable to the scatter in the observations of Bower et al.(1992)of ellipticals

Evolution of the Hubble Sequence

17

Figure 15.The colour-magnitude relation in bins of redshift for a sample of 730galaxies selected from our models with magnitudes 17.5≤I AB ≤22.5.Triangles indicate elliptical galaxies,crosses S0’s,circles spirals and stars objects that have a bulge component containing less than 5%of the total light.The vertical line shows the cut in colour that we have adopted to separate the galaxies into red and blue subsamples.

in the Coma and Virgo clusters,when one takes into account that the observations are of the cluster cores,whereas our models cannot revolve within the virial radius.A ?at colour-magnitude relation in the models results from the fact that the bulk of the stars that end up in ellipticals formed at high redshift even though the galaxies themselves were not assem-bled until much later.The small scatter results,in part,from the ?atness of this relation.The observed colour-magnitude diagram of cluster ellipticals is,of course,not completely ?at,but has a small gradient of increasing redness with in-creasing brightness.In the context or our models this gradi-ent must be due to metallicity e?ects which,in the absence

of the appropriate stellar population synthesis models,we have been forced to neglect.We plan to study these e?ects in a forthcoming paper using Worthey’s (1994)new,metal-licity dependent synthesis models.Whether our models will be able to reproduce the observed gradient whilst retaining a small scatter in colour remains an open question.An important prediction of our models is the similarity between the colour-magnitude diagrams at redshifts ～0.5and at the present day.The main evolutionary e?ect is a blueing of the galaxies by about 0.15mag in B-V,similar to that observed in cluster ellipticals by Arag′o n-Salamanca et al.(1993).This results from a combination of passive evo-

18 C.M.Baugh,S.Cole,C.S.Frenk

Figure16.Luminosity functions of galaxies in our mock catalogue as a function of colour and redshift.The red galaxies are shown in the left-hand panels and the blue galaxies are shown in the right-hand panels.The galaxies are binned in redshift and the redshift increases down the plot,as indicated in the upper-left corner of each panel.The open points with error bars show the best estimate of the CFRS luminosity function of Lilly et al.(1995)(their Figure3).The?lled points show the evolution of the luminosity function of ’red’and’blue’galaxies in a mock CFRS catalogue constructed from our model.The dotted line is for reference and shows the Schechter function given by Loveday et al.(1992)

Evolution of the Hubble Sequence19

lution of the stellar populations and evolution of the star formation rate.Other than that,our models of elliptical galaxies predict almost no increase in the scatter in colour at a given luminosity out to z?0.5.For spirals,there is a moderate increase in the scatter at high redshift.Both at z=0.5and at the present,the mean B-V colours of ellipti-cals and spirals in clusters are almost independent of cluster richness.

Rich clusters in our model contain a di?erent mix of morphological types if they collapse at redshift zero,com-pared with clusters that collapse at z=0.5.Kau?mann (1995a)has demonstrated that a cluster of a given mass at high redshift is assembled more rapidly than a cluster of the same mass at the present day.In the context of our model, this means that the lifetime of a dark matter halo that is a progenitor of a cluster at high redshift will typically be much shorter than the timescale for galaxy mergers.Hence the population of galaxies that become members of high red-shift clusters shows a higher fraction of spirals,in agreement with HST observations of z～0.4clusters(Dressler et al. 1994).The dark matter halo lifetime for low redshift cluster progenitors is longer,and so galaxy mergers are more likely. Hence in our model rich clusters that form at low redshift are dominated by E/S0galaxies,reproducing the morphology-density relation discovered in the real universe by Dressler (1980).

We have compared the predictions of our model with ob-servations of the luminosity function at di?erent redshifts. When the model galaxies are separated by colour,the lu-minosity function of the blue galaxies evolves in steepness and brightness between z～0.1and z～0.6,remaining fairly constant up to z～1.The luminosity function of the red galaxies stays approximately constant with redshift.At higher redshifts,we do?nd objects that have blue colours and which are bulge dominated.This is expected if these galaxies have recently experienced a merger event,with the blue colours due to a burst having taken place in the case of a violent merger or because stars that had recently formed in a disk have now been incoporated into the bulge for the case of a minor merger.

The calculations presented in this paper serve to demon-strate that the simplest possible prescription for the distinc-tion between disks and spheroids that is compatible with hierarchical clustering goes a long way towards explaining many of the systematic trends observed in the galaxy popu-lation.Our models are necessarily idealised and ignore pro-cesses such as internal galactic phenomena or dynamical friction in clusters,which have almost certainly helped to shape the complex morphologies of real galaxies.It is there-fore quite remarkable that they are able to account,at least in an approximate way,for such fundamental properties as the morphology-density relation,the colour-magnitude di-agram,the Butcher-Oemler e?ect and the evolution of the luminosity function of galaxies of di?erent colours.A num-ber of critical observations such as measurement of colour-magnitude diagrams of cluster galaxies at high redshift will help to test this paradigm.ACKNOWLEDGEMENTS

We would like to thank Stephane Charlot for providing us with a revised stellar population model.Richard Nolthe-nius kindly provided his data in electronic form.We thank Richard Bower for his detailed comments on an earlier ver-sion of this paper and for the loan of statistical software. We acknowledge useful conversations with Guinivere Kau?-mann,Gary Mamon and Julio Navarro.CMB acknowledges a PPARC research assistantship and SMC a PPARC Ad-vanced Fellowship.This work was supported in part by a PPARC Rolling Grant.

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五年级上册成语解释及近义词反义词和造句大全.doc

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The way常见用法

The way 的用法 Ⅰ常见用法： 1)the way+ that 2)the way + in which（最为正式的用法） 3)the way + 省略（最为自然的用法） 举例：I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法： 在当代美国英语中，the way用作为副词的对格，“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2）The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3）The way =how/ how much No one can imagine the way he missed her. 4）The way =because

悲惨的近义词反义词和造句

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争，往往是悲惨的、没有光华的、没有幸福的，在孤独与静寂中展开的斗争。……他们只能依靠自己，可是有时连最强的人都不免于在苦难中蹉跎。罗曼·罗兰 8.伟大的心胸，应该表现出这样的气概用笑脸来迎接悲惨的厄运，用百倍的勇气来应付开始的不幸。鲁迅人在逆境里比在在顺境里更能坚强不屈。遇厄运时比交好运时容易保全身心。 9.要抓紧时间赶快生活，因为一场莫名其妙的疾病，或者一个意外的悲惨事件，都会使生命中断。奥斯特洛夫斯基。 10.在我一生中最悲惨的一个时期，我曾经有过那类的想法：去年夏天在我回到这儿附近的地方时，这想法还缠着我;可是只有她自己的亲自说明才能使我再接受这可怕的想法。 11.他们说一个悲惨的故事是悲剧，但一千个这样的故事就只是一个统计了。 12.不要向诱惑屈服，而浪费时间去阅读别人悲惨的详细新闻。 13.那起悲惨的事件深深地铭刻在我的记忆中。 14.伟大的心胸，应该用笑脸来迎接悲惨的厄运，用百倍的勇气来应付一切的不幸。 15.一个人要发现卓有成效的真理，需要千百万个人在失败的探索和悲惨的错误中毁掉自己的生命。门捷列夫 16.生活需要爱，没有爱，那些受灾的人们生活将永远悲惨;生活需要爱，爱就像调味料，使生活这道菜充满滋味;生活需要爱，爱让生活永远充满光明。

The way的用法及其含义(二)

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(完整版)the的用法

定冠词the的用法： 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...

“the way+从句”结构的意义及用法

“tｈｅwａｙ+从句”结构的意义及用法 首先让我们来看下面这个句子: Ｒead the foｌloｗｉnｇpassagｅａnd talkａbout ｉt wi ｔh your classmaｔes．Try tｏｔeｌl whaｔyｏu thiｎk ｏf Tom aｎd ｏｆｔhe ｗay the chiｌｄrenｔrｅated ｈim. 在这个句子中，ｔhe waｙ是先行词,后面是省略了关系副词that或in whｉch的定语从句。 下面我们将叙述“the ｗaｙ+从句”结构的用法。 1.tｈe wａy之后，引导定语从句的关系词是tｈat而不是hoｗ,因此，<<现代英语惯用法词典＞＞中所给出的下面两个句子是错误的：Ｔhｉs is ｔｈeｗayｈowｉtｈａppened. This is the way how he ａlwａｙs treats me. 2．在正式语体中,thaｔ可被in which所代替;在非正式语体中，ｔhat则往往省略。由此我们得到theｗay后接定语从句时的三种模式：1) tｈe ｗaｙ＋ｔhａt-从句２）the way +ｉn whiｃh－从句3) the ｗay +从句 例如：Ｔｈe way(in whiｃh ，thａt) ｔhｅｓｅｃomｒade ｓloｏｋａｔｐrobｌems is wrong．这些同志看问题的方法

不对。 Ｔｈｅｗａy(that ,ｉn ｗhiｃh)yoｕ’ｒe doinｇit is comple ｔeｌy crａzy.你这么个干法,简直发疯。 Wｅａdmiｒｅd him for thｅｗay ｉｎｗhｉch he fａｃeｓdiｆficultieｓ． Waｌlａｃe ａｎd Ｄarwiｎｇreed ｏn the way ｉｎwhi ｃh ｄｉfｆｅrｅnt forms ｏf life had ｂegｕn.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 Thｉs is ｔｈe ｗaｙ（tｈａｔ) hｅdｉd it. I lｉkeｄｔhe waｙ(ｔhat) ｓｈeｏｒganized ｔhe ｍeetｉng． 3.theｗay(tｈat)有时可以与hｏw(作“如何”解）通用。例如： That’s tｈe ｗaｙ(tｈaｔ) shｅspoke. = Tｈat’s how shｅspoke.

知己的近义词反义词及知己的造句

知己的近义词反义词及知己的造句 本文是关于知己的近义词反义词及知己的造句，感谢您的阅读！ 知己的近义词反义词及知己的造句知己 基本解释：顾名思义是了解、理解、赏识自己的人，如"知己知彼，百战不殆";更常指懂你自己的挚友或密友，它是一生难求的朋友，友情的最高境界。正所谓:"士为知己者死"。 1.谓了解、理解、赏识、懂自己。 2.彼此相知而情谊深切的人。 【知己近义词】 亲信，好友，密友，心腹，挚友，深交，相知，知交，知友，知心，知音，石友，老友，至友 【知己反义词】 仇人敌人陌路 【知己造句】 1、我们想要被人爱、想拥有知己、想历经欢乐、想要安全感。 2、朋友本应是我们的亲密知己和支持者，但对于大多数人来说，有一些朋友比起帮助我们，更多的却是阻碍。 3、那么，为什么你就认为，随着年龄的增长，比起女人来男人们的知己和丰富的人际关系更少，因此一般容易更孤独呢？ 4、他成了我的朋友、我的知己、我的顾问。 5、无论在我当州长还是总统的时候，布鲁斯都是我的密友、顾问和知己。他这样的朋友人人需要，也是所有总统必须拥有的。

6、波兰斯基有着一段声名卓著的电影生涯，也是几乎所有电影界重要人物们的挚友和同事，他们是知己，是亲密的伙伴。 7、搜索引擎变成了可以帮追我们的忏悔室，知己，信得过的朋友。 8、这样看来，奥巴马国家安全团队中最具影响力的当属盖茨了――但他却是共和党人，他不会就五角大楼以外问题发表看法或成为总统知己。 9、我们的关系在二十年前就已经和平的结束了，但在网上，我又一次成为了他精神层面上的评论家，拉拉队，以及红颜知己。 10、这位“知己”，作为拍摄者，站在距离电视屏幕几英尺的地方对比着自己年轻版的形象。 11、父亲与儿子相互被形容为对方的政治扩音筒、知己和后援。 12、这对夫妻几乎没有什么至交或知己依然在世，而他们在后纳粹时期的德国也不可能会说出实话的。 13、她把我当作知己，于是，我便将她和情人之间的争吵了解得一清二楚。 14、有一种友谊不低于爱情；关系不属于暖昧；倾诉一直推心置腹；结局总是难成眷属；这就是知己！ 15、把你的治疗师当做是可以分享一切心事的知己。 16、莉莉安对我敞开心胸，我成了她的知己。 17、据盖洛普民意调查显示，在那些自我认同的保守党人中，尽管布什仍维持72%支持率，但他在共和党领导层中似乎很少有几位知

way 用法

表示“方式”、“方法”，注意以下用法： 1.表示用某种方法或按某种方式，通常用介词in(此介词有时可省略)。如： Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法，其后可接不定式或of doing sth。 如： It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词)，也可跟由that 或in which 引导的定语从句，但是其后的从句不能由how 来引导。如： 我不喜欢他说话的态度。 正：I don’t like the way he spoke. 正：I don’t like the way that he spoke. 正：I don’t like the way in which he spoke. 误：I don’t like the way how he spoke. 4.注意以下各句the way 的用法： That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看，你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题： ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A，而不选其他几项，则要弄清选项中含way的四个短语的不同意义和用法，下面我们就对此作一归纳和小结。 一、in a way的用法 表示：在一定程度上，从某方面说。如： In a way he was right.在某种程度上他是对的。注：in a way也可说成in one way。 二、on the way的用法 1、表示：即将来(去)，就要来(去)。如： Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示：在路上，在行进中。如： He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示：(婴儿)尚未出生。如： She has two children with another one on the way.她有两个孩子，现在还怀着一个。 She's got five children，and another one is on the way.她已经有5个孩子了，另一个又快生了。 三、by the way的用法

小学语文反义词仿照的近义词反义词和造句

仿照的近义词反义词和造句 仿照的近义词 【仿制解释】：仿造：～品 【模仿解释】：个体自觉或不自觉地重复他人的行为的过程。是社会学习的重要形式之一。尤其在儿童方面，儿童的动作、语言、技能以及行为习惯、品质等的形成和发展都离不开模仿。可分为无意识模仿和有意识模仿、外部模仿和内部模仿等多种类型。 仿照的反义词 【独创解释】：独特的创造：～精神ㄧ～一格。 仿照造句 一、老师让我们仿照黑板上的图画一幅画。 二、仿照下面的句式，以“只有”开头，写一结构与之相似的复句。 三、仿照例句的句子，在下面两句的横线上补写相应的内容。 四、仿照例句，以“记忆”或“友情”开头，另写一句话。 五、仿照下面两个例句，用恰当的词语完成句子，要求前后语意关联。 六、仿照开头两句句式，通过联想，在后面两句横线上填上相应的词语。 七、仿照所给例句，用下面的词展开联想，给它一个精彩的解释。 八、仿照例句，以“你”开头，另写一个句子。 九、仿照下列句式，续写两个句子，使之与前文组成意义相关的.句子。 十、我们也仿照八股文章的笔法来一个“八股”,以毒攻毒,就叫做八大罪状吧。

十一、仿照例句，任选一种事物，写一个句子。 十二、仿照下面一句话的句式和修辞，以“时间”开头，接着写一个句子。 十三、仿照例句，以“热爱”开头，另写一句子。 十四、仿照下面的比喻形式，另写一组句子。要求选择新的本体和喻体，意思完整。 十五、根据语镜，仿照划线句子，接写两句，构成语意连贯的一段话。 十六、仿照下面句式，续写两个句式相同的比喻句。 十七、自选话题，仿照下面句子的形式和修辞，写一组排比句。 十八、仿照下面一句话的句式，仍以“人生”开头，接着写一句话。 十九、仿照例句的格式和修辞特点续写两个句子，使之与例句构成一组排比句。 二十、仿照例句，另写一个句子，要求能恰当地表达自己的愿望。 二十一、仿照下面一句话的句式，接着写一句话，使之与前面的内容、句式相对应，修辞方法相同。 二十二、仿照下面一句话的句式和修辞，以“思考”开头，接着写一个句子。 二十三、仿照下面例句，从ABCD四个英文字母中选取一个，以”青春”为话题，展开想象和联想，写一段运用了比喻修辞格、意蕴丰富的话，要求不少于30字。 二十四、仿照下面例句，另写一个句子。 二十五、仿照例句，另写一个句子。 二十六、下面是毕业前夕的班会上，数学老师为同学们写的一句赠言，请你仿照它的特点，以语文老师的身份为同学们也写一句。

The way的用法及其含义(一)

The way的用法及其含义（一） 有这样一个句子：In 1770 the room was completed the way she wanted. 1770年，这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么？其意义如何？在阅读时，学生经常会碰到一些含有the way 的句子，如：No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中，the way之后的部分都是定语从句。第一句的意思是，“没人知道他是怎样发明这台机器的。”the way的意思相当于how；第二句的意思是，“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中，the way也是as的含义。随着现代英语的发展，the way的用法已越来越普遍了。下面，我们从the way的语法作用和意义等方面做一考查和分析： 一、the way作先行词，后接定语从句 以下3种表达都是正确的。例如：“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如：“火灾如何发生的，有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.

暗示的近义词和反义词 [暗示的近义词反义词和造句]

暗示的近义词和反义词[暗示的近义词反义词和造句] 【暗示解释】：用含蓄、间接的方式使他人的心理、行为受到影响。下面小编就给大家整理暗示的近义词，反义词和造句，供大家学习参考。 暗示近义词 默示 示意 暗指 暗意暗示反义词 明说 表明 明言暗示造句 1. 他的顶级助手已经暗示那可能就在不久之后，但是避免设定具体的日期。 2. 一些观察家甚至暗示他可能会被送到了古拉格。 3. 要有积极的心理暗示，达成目标的好处不够充分，画面不够鲜明那它对你的吸引力就不够强烈，你就不易坚持下去! 4. 不要经常去试探男人，更不要以分手做为威胁，当你经常给他这种心理暗示，他的潜意识就会做好分手的打算。 5. 向读者暗示永远不必为主角担心，他们逢凶化吉，永远会吉人天相。 6. 约她一起运动，不要一下跳跃到游泳，可以从羽毛球网球开始，展示你的体魄和运动细胞，流汗的男人毫无疑问是最性感的，有意无意的裸露与靠近，向她暗示你的运动能力。 7. 正如在上一个示例所暗示的，只有在这些对象引用内存中同一个对象时，它们才是相同的。 8. 渥太华此时打出中国牌，巧妙地对美国这种行为作出警告，暗示美国如果长期这样下去的话，美国将自食其果。 9. 团长用震撼人心的嗓音喊道，这声音对他暗示欢乐，对兵团暗示森严，对前来校阅阅兵的首长暗示迎迓之意。 10. 渥太华此时打出中国牌，巧妙地对美国这种行为作出警告，暗示美国如果长期这样下去的话，美国将自食其恶果。 11. 我们需要邀请用户，为他们描述服务产品有多少好，给他们解释为什么他们需要填那些表单并且暗示他们会因此得到利益的回报。 12. 她对暗示她在说谎的言论嗤之以鼻。 14. 在力士参孙中，整首诗都强烈暗示着弥尔顿渴望他自己也能像参孙一样，以生命为代价，与敌人同归于尽。 15. 戴维既然问将军是否看见天花板上的钉子，这就暗示着他自己已看见了，当将军做了肯定的答复后，他又说自己看不见，这显然是自相矛盾。 16. 自我暗示在我们的生活中扮演着重要角色。如果我们不加以觉察，通常它会与我们作对。相反地，如果你运用它，它的力量就可以任你使唤。 17. 纳什建议太阳招兵买马，暗示去留取决阵容实力。 18. 同时，还暗示了菊既不同流俗，就只能在此清幽高洁而又迷漾暗淡之境中任芳姿憔悴。 19. 学习哲学的最佳途径就是将它当成一个侦探故事来处理：跟踪它的每一点蛛丝马迹每一条线索与暗示，以便查出谁是真凶，谁是英雄。 20. 不要经常去试探你的伴侣，更不要以分手做为威胁，试探本身就是一种不信任，当

放弃的近义词反义词和造句

放弃的近义词反义词和造句 下面就给大家整理放弃的近义词，反义词和造句，供大家学习参考。 放弃的近义词【废弃解释】：抛弃不用：把～的土地变成良田ㄧ旧的规章制度要一概～。 【丢弃解释】：扔掉;抛弃：虽是旧衣服，他也舍不得～。 放弃的反义词【保存解释】：使事物、性质、意义、作风等继续存在，不受损失或不发生变化：～古迹ㄧ～实力ㄧ～自己，消灭敌人。 放弃造句(1) 运动员要一分一分地拼，不能放弃任何一次取胜的机会。 (2) 我们不要放弃每一个成功的机会。 (3) 敌军招架不住，只好放弃阵地，狼狈而逃。 (4) 为了农村的教育事业，姐姐主动放弃了调回城市的机会。 (5) 都快爬到山顶了，你却要放弃，岂不功亏一篑?(6) 纵使遇到再大的困难，我们也要勇往直前，不轻言放弃。 (7) 逆境中的他始终没有放弃努力,仍满怀信心,期待着峰回路转的那一天。 (8) 听了同学的规劝,他如梦初醒,放弃了离家出走的想法。 (9) 因寡不敌众,我军放弃了阵地。 (10) 要日本帝国主义放弃侵华野心,无异于与虎谋皮。 (11) 永不言弃固然好，但有时放弃却也很美。

(12) 他这种放弃原则、瓦鸡陶犬的行径已经被揭露出来了。 (13) 适当放弃，做出斩钉截铁的决定，才能成为人生的赢家。 (14) 他委曲求全地放弃自己的主张，采纳了对方的意见。 (17) 我们要有愚公移山一样的斗志，坚持不懈，永远不放弃，去登上梦想的彼岸!(18) 只要有希望，就不能放弃。 (19) 为了大局着想，你应该委曲求全地放弃自己的看法。 (20) 既然考试迫在眉睫，我不得不放弃做运动。 (21) 即使没有人相信你，也不要放弃希望。 (22) 无论通往成功的路途有多艰辛，我都不会放弃。 (23) 在困难面前，你是选择坚持，还是选择放弃?(24) 无论前路多么的漫长，过程多么的艰辛，我都不会放弃并坚定地走下去。 (25) 你不要因为这点小事就英雄气短,放弃出国深造的机会。 (26) 像他这样野心勃勃的政客，怎么可能放弃追求权力呢?(27) 鲁迅有感于中国人民愚昧和麻木,很需要做发聋振聩的启蒙工作,于是他放弃学医,改用笔来战斗。 (28) 我们对真理的追求应该坚持不懈，锲而不舍，绝不能随便放弃自己的理想。 (29) 感情之事不比其他，像你这样期盼东食西宿，几个男友都捨不得放弃，最后必定落得一场空。 (30) 爷爷临终前的话刻骨铭心，一直激励着我努力学习，无论是遇到多大的困难险阻，我都不曾放弃。

way 的用法

way 的用法 【语境展示】 1. Now I’ll show you how to do the experiment in a different way. 下面我来演示如何用一种不同的方法做这个实验。 2. The teacher had a strange way to make his classes lively and interesting. 这位老师有种奇怪的办法让他的课生动有趣。 3. Can you tell me the best way of working out this problem? 你能告诉我算出这道题的最好方法吗？ 4. I don’t know the way (that / in which) he helped her out. 我不知道他用什么方法帮助她摆脱困境的。 5. The way (that / which) he talked about to solve the problem was difficult to understand. 他所谈到的解决这个问题的方法难以理解。 6. I don’t like the way that / which is being widely used for saving water. 我不喜欢这种正在被广泛使用的节水方法。 7. They did not do it the way we do now. 他们以前的做法和我们现在不一样。 【归纳总结】 ●way作“方法，方式”讲时，如表示“以……方式”，前面常加介词in。如例1； ●way作“方法，方式”讲时，其后可接不定式to do sth.，也可接of doing sth. 作定语，表示做某事的方法。如例2，例3；

体面的近义词-反义词及造句

体面的近义词|反义词及造句 我们还必须迅速采取行动，为实现社会包容和人人体面工作营造有利的环境。下面是小编精选整理的体面的近义词|反义词及造句，供您参考，欢迎大家阅读。 体面的近义词： 面子、合适、美观、颜面、场合、场面、排场、得体、好看、局面 体面的反义词： 难听、寒碜、邋遢、寒酸、难看 体面造句 1、我认为，帖在墙面上的证书，并不能使你成为一个体面的人。 2、他是那里唯一的看上去很体面的人;我认为他从来没有这样好看过。 3、所有的美国人都是好的，体面的人们每天都在践行着他们的责任。 4、美国人民慷慨、强大、体面，这并非因为我们信任我们自己，而是因为我们拥有超越我们自己的信念。 5、工人就是工人，无论他们来自哪里，他们都应该受到尊重和尊敬，至少因为他们从事正当的工作而获得体面的工资。 6、然而反之有些孩子可能就是多少有些体面的父母的不良种子这一概念却令人难以接受。

7、如果奥巴马能够成就此功，并且帮助一个体面的伊拉克落稳脚跟，奥巴马和民主党不仅是结束了伊拉克战争，而是积极从战争中挽救。 8、而且，等到年纪大了退休时，他们希望能得到尊重和体面的对待。 9、爸爸，您倒对这件事处理得很体面，而我想那可能是我一生中最糟糕的一个夜晚吧。 10、有一些积极的东西，低于预期的就业损失索赔和零售销售是体面的。 11、如果你努力工作，你就能有获得一份终生工作的机会，有着体面的薪水，良好的福利，偶尔还能得到晋升。 12、体面的和生产性的工作是消除贫困和建立自给自足最有效的方法之一。 13、同时，他是一个仁慈、温和、体面的人，一个充满爱的丈夫和父亲，一个忠实的朋友。 14、几周前我们刚讨论过平板电脑是如何作为一个体面且多产的电子设备，即使它没有完整的键盘，在进行输入时会稍慢些。 15、什么才是生活体面的标准? 16、我们还必须迅速采取行动，为实现社会包容和人人体面工作营造有利的环境。 17、她告诉我人们都担心是不是必须把孩子送到国外去学习，才能保证孩子们长大后至少能过上体面正派的生活。

the-way-的用法讲解学习

t h e-w a y-的用法

The way 的用法 "the way+从句"结构在英语教科书中出现的频率较高, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 一.在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮.

近义词反义词大全有关聆听的反义词近义词和造句

近义词反义词大全有关聆听的反义词近义词和造句 【聆听解释】：1.汉扬雄《法言.五百》:"聆听前世﹐清视在下﹐鉴莫近于斯矣。"后多用于书面语﹐常指仔细注意地听。下面就给大家聆听的反义词，近义词和造句，供大家学习参考。 嘱咐 [注释]1.叮嘱，吩咐 倾听 [注释]1.侧着头听。 2.细听;认真地听 凝听 [注释]1.聚精会神地听 谛听 [注释]注意地听;仔细听：侧耳谛听 细听 [注释]… 1. 学校应充分利用社会的各种，调动一切可以调动的力量，应尽一切可能请进名师专家，让教师和学生有较多的机会聆听大师的声音、与大师对话。这多少会机器他们向往大师、成为大师的冲动，多少会使他们觉得大师就在身边，大师并不遥远。 2. 今天妈妈带我来到了这个美丽的大安森林公园玩，这儿有漂亮的花儿和绿油油的树，草，看起来像一个我好想好想要的花园。树

上有小鸟儿在唱歌，有蝉声在帮忙和弦，树下有小朋友再安静仔细聆听著这最自然的交响曲。 3. 静静聆听那滴滴答答的声音，不知在为谁倾诉?她在偶尔低语，偶尔高唱，偶尔呻吟，偶尔叹息，生动灵活，充满了立体与层次之美，在心灵中轻轻一吻，便触发了思绪，这思绪时而短暂，时而绵长，时而深沉，时而悠远…… 4. 九月的手掌拂去小溪夏日的狂躁，用心聆听着秋日的私语，温顺地弹唱着九月醉人的秋歌，惹得天空湛蓝高远，碧空如洗。 5. 我光着脚丫，踩着海水，注视着波光粼粼的海面，听着哗哗的响声，那声音好像高超演奏家的激越的钢琴曲，又像歌唱家的雄浑的进行曲，那声音使胸膛激荡，热血奔涌，啊，我多么愿意聆听大海老人的谆谆教诲啊! 6. 雪花飘飘，寒风阵阵，我细细地聆听着寒风谱写成的有声有色的乐谱，为雪花的舞步增添一些光彩。寒风真像一位默默为雪花服务的人。过了一会儿，又为雪花写了一篇朗朗上口的诗歌，一会儿又为她热烈地鼓起了清脆的掌声。

way的用法总结大全

way的用法总结大全 way的用法你知道多少，今天给大家带来way的用法，希望能够帮助到大家，下面就和大家分享，来欣赏一下吧。 way的用法总结大全 way的意思 n. 道路,方法,方向,某方面 adv. 远远地，大大地 way用法 way可以用作名词 way的基本意思是“路,道,街,径”,一般用来指具体的“路,道路”,也可指通向某地的“方向”“路线”或做某事所采用的手段,即“方式,方法”。way还可指“习俗,作风”“距离”“附近,周围”“某方面”等。 way作“方法,方式,手段”解时,前面常加介词in。如果way前有this, that等限定词,介词可省略,但如果放在句首,介词则不可省略。

way作“方式,方法”解时,其后可接of v -ing或to- v 作定语,也可接定语从句,引导从句的关系代词或关系副词常可省略。 way用作名词的用法例句 I am on my way to the grocery store.我正在去杂货店的路上。 We lost the way in the dark.我们在黑夜中迷路了。 He asked me the way to London.他问我去伦敦的路。 way可以用作副词 way用作副词时意思是“远远地,大大地”,通常指在程度或距离上有一定的差距。 way back表示“很久以前”。 way用作副词的用法例句 It seems like Im always way too busy with work.我工作总是太忙了。 His ideas were way ahead of his time.他的思想远远超越了他那个时代。 She finished the race way ahead of the other runners.她第一个跑到终点,远远领先于其他选手。 way用法例句

终于的近义词,反义词及造句

终于的近义词，反义词及造句 …终究[注释]副词。 总：总归;毕竟;最终：我们只要把事情办好，人们终究会相信我们的|腐朽的东西终究要灭…到底[注释]1.直到尽头。 2.始终;从头到尾。 3.毕竟;究竟。 …结果[注释]结果1在一定阶段，事物发展所达到的最后状态：优良的成绩，是长期刻苦学习的～ㄧ经过一番争论…终归[注释]1.传说中神兽名。 2.终究;毕竟。 …究竟终于的反义词：起初、最初、原来、依旧、起先终于的造句：(1) 盼望了一个冬天的雪花，下午终于飘飘洒洒满天飞舞般降落。 同事们也如孩子般奔向办公室的走廊，欣喜地用手去接冰凉的小雪花再用盆子收拢些飘舞的小雪花。 隔窗望去，天地之间因突然多了这白色的小精灵而愈发显得美丽。 (2) 快乐的暑假终于到了，我可以开开心心痛痛快快地玩一顿了!当然，在这之前，我也会好好安排一下我的暑假生活，使我过个既快乐又充实的暑假，我快乐的暑假生活。 (3) 坚韧，让沙石煎熬住大海的蹂躏，终于化作璀璨的珍珠;坚韧，让天空忍受住雨水倾盆的阴霾，终于看见那一道彩虹;坚韧，让泉水忘记流进山谷崎岖的历程，终于汇入蔚蓝无垠的大海。

它的叶子正面是身绿色的，反面是浅绿的，经脉上还有一些毛绒绒的小细毛。 又过了几天，含羞草的花蕾也长出来了，圆溜溜的，紫红色，还有着一些像针一样的东西，非常美丽。 (5) 漫长而炎热的夏天终于过去了，凉爽怡人的秋天来到了。 (6) 随着天空被点燃，太阳也终于露出脸来，它没有害羞，而是大大方方地把它独特的热情展示给我们，毫不吝惜地奖光芒撒向大地。 (7) 大约过了二十分钟，太阳终于挣脱了大地妈妈的怀抱，在崇山俊岭之间冉冉升起，真像个大红球，又像气得涨红了脸。 (8) 半个月的低烧，终于有了好转，高烧了……(9) 夏天的雨后，太阳冲出乌云的包围，终于露出了整张脸，此时阳光直直的，却不呆板、单调，它们穿梭在树枝之间，织成一道道金色的丝，将鱼后的水珠串成一串金黄的珍珠。 夏天少有的凉意伴着美丽的阳光，令人沁透心脾。 (10) 终于到达了果园。 我们忽然发现，果园里还种了一些菊花。 这些菊花有红的蓝的黄的白的……它们颜色不同，姿态也不同：菊花们有的含苞欲放，有的开了一半，有的已经绽开了笑脸……千姿百态，十分美丽。 (11) 发改委终于超越了统计局，说北京人均绿地是巴黎两倍。 最牛回复：“是算上了开心农场吧?。

the_way的用法大全教案资料

t h e_w a y的用法大全

The way 在the way+从句中, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 如果怕弄混淆，下面的可以不看了 另外，在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮. the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的