Probing Halos of Galaxies at Very Large Radii using Background QSOs

a r X i v :a s t r o -p h /0410288v 1 11 O c t 2004

Probing Halos of Galaxies at Very Large Radii using Background

QSOs 1

S.C?o t′e

Canadian Gemini O?ce,Herzberg Institute of Astrophysics,National Reseach Council of

Canada,5071West Saanich Road,Victoria,B.C.,Canada,V9E 2E7

Stephanie.Cote@nrc.ca

R.F.G.Wyse

Department of Physics and Astronomy,Johns Hopkins University,3400N.Charles Street,

Baltimore,MD 21218,USA

wyse@https://www.doczj.com/doc/c41390693.html,

C.Carignan

Observatoire du Mont M′e gantic et D′e partement de Physique,Universit′e de Montr′e al,CP

6128,Succ.centre ville,Montr′e al,H3C 3J7,Canada

carignan@astro.umontreal.ca

K.C.Freeman

Research School of Astronomy and Astrophysics,Mount Stromlo Observatory,ANU,

Weston Creek ACT 2611,Australia

kcf@https://www.doczj.com/doc/c41390693.html,.au

T.Broadhurst

School of Physics and Astronomy,Tel-Aviv University,Tel-Aviv 69978,Israel

tjb@wise.tau.ac.il

ABSTRACT

Gaseous halos of nine nearby galaxies (with redshifts cz <6000km s ?1)were

probed at large galactocentric radii using background quasars observed with HST GHRS and STIS.The projected quasar-galaxy separations range from 55to

387h ?175kpc.Ly αabsorption lines were successfully detected in the spectra

of?ve quasars,at impact parameters of up to～170h?175kpc from the center of

the nearby galaxy,and in each case at wavelengths consistent with the galaxy’s

redshift.Our observations include the lowest redshift Lyαlines detected to date.

HI velocity?elds were obtained at the VLA for three of the galaxies in our sample

(and in one case was available from the literature),to derive their rotation curves.

When comparing the inner rotation curves of the galaxies with the velocity at

large radius provided by the Lyαline it is apparent that it is very di?cult to

explain the observed Lyαvelocity as due to gas in an extended rotating disk.In

most cases one would need to invoke large warps in the outer gas disks and also

thick gas disks in order to reconcile the observed velocities with the predicted

ones.Indeed,in one case the Lyαline velocity indicates in fact counter-rotation

with respect to the inner disk rotation.In light of these results we conclude

that in a typical galaxy there is no longer detectable atomic gas corotating in

an extended disk at radii>35α?1,whereα?1is the stellar disk exponential

scale-length.The cosmic web is the most likely origin for the detected Lyαlines.

Our observations con?rm the Bowen et al.(2002)correlation of equivalent widths

with the local volume density of galaxies around the sightline,and the observed

equivalent widths of the lines are consistent with expectations of the cosmic web.

Subject headings:galaxies:halos—galaxies:spiral—quasars:absorption lines

—galaxies:ISM

1.Introduction

Rotation curves are the best tool to study the dark matter halos of galaxies,and the most extended ones will better constrain the dark matter halo parameters.Rotation curves derived from neutral hydrogen(HI)observations enable us to probe the dark matter potential to distances of at most20to25α?1(whereα?1is the optical disk exponential scale length), for gas-rich late-type spiral galaxies with particularly extended HI(eg.NGC2841from Begeman1987or NGC2915from Meurer et al.1996).But it is not possible to obtain any kinematical data with21cm emission further out than the radius at which the gas density falls to levels of a few times1019atoms cm?2,even with very sensitive observations,as the HI column falls o?sharply beyond this point(eg.the’HI Edge’observed in NGC3198,van

Gorkom1991).This sharp truncation of the HI distribution is believed to be the result of

ionization of the atomic gas by the extragalactic UV radiation?eld(as predicted by Silk

&Sunyaev1976).At lower column densities the neutral fraction is therefore predicted to

drop o?dramatically in comparison to the total(ionized)hydrogen column(see Maloney

1993).Some studies have attempted to detect the faint ionized gas just beyond the HI limit

from recombination emission in Hα.Depending on the volume density of the plasma at the

critical column density where the outer disk becomes optically thin to this radiation(about

N HI～3×1019cm?2for NGC3198),the emission measure from recombination radiation expected to be emitted by this ionized gas is only0.025to0.25cm?6pc(Maloney1993).

The only reported detection of recombination radiation so far is that of NGC253for which

sensitive Fabry-Perot observations by Bland-Hawthorn et al.(1997)managed to extend the

HI rotation curve from1.2to1.4R25,with measured surface brightness values in Hαfrom

80to40mR(millirayleighs,where1rayleigh=106/4πphotons cm?2s?1sr?1or2.78cm?6pc

at Hα).But at this level,as pointed out by the authors,the emission is probably not due to

recombination after ionization by the metagalactic background,but rather from hot young

stars near the center of the galaxy ionizing the warped outer HI disk.

If indeed spiral galaxies have extended(mostly ionized)gas disks it should then be

possible to detect them in absorption in the spectrum of a bright background quasar,down

to HI column densities of only～1013atoms cm?2.With such a suitably placed UV-bright

background object one could obtain kinematical information on that galaxy’s outer rotation

curve out to30to40α?1or more.At such radii the data could potentially reveal the extent

of the dark matter halo,and constrain the mass pro?le out to such large galactocentric

radii.This could then provide strong tests of cosmological galaxy formation scenarios.For

example,according to the rotation curves predicted by Cold Dark Matter-dominated N-body

simulations(e.g.Navarro,Frenk&White1996)in low-mass dwarf galaxies we should detect

a turn-down in the rotation curve if we could get data points just15or20%further out in

radius than currently mapped by HI observations.This matching of a Lyαabsorption line

velocity with the kinematics of the nearest galaxy has already been attempted,originally by

Barcons et al.(1995),who found that for two galaxies at z=0.075and0.09the Lyαvelocities

as measured from background QSOs spectra at impact parameters64h?175kpc(=16α?1)and

83h?175kpc(=35α?1),were consistent with gas in extended gaseous haloes co-rotating with

the inner stellar disks(with h?175=H0/75where H0is the Hubble constant and q0=0).On

the other hand,Ho?man et al.(1998)found that the dwarf galaxy MCG+00-32-16,which

is the closest galaxy to the low redshift Lyαsystem in the sightline of3C273,has an HI disk

which would be counter-rotating compared to the Lyαvelocity.In this case however the

impact parameter is204kpc which for the dwarf galaxy represents about153α?1,in other

words an excessively large radius to expect the extended gas halo to reach.More recently

Steidel et al.(2002)have obtained long-slit spectra of5intermediate redshift galaxies(0.44≤z≤0.66)in the proximity of MgII absorbers sightlines(with projected separations from19 to95h?175kpc),and succeeded in reasonably matching the MgII absorbers’velocities with the galaxies’rotation curves,but only when setting various disk thicknesses and velocity scale heights(describing the velocity fall-o?with z-height above the plane)case by case.

Our approach here is the reverse.Instead of identifying and analysing the galaxies found near the line-of-sight of a quasar exhibiting a known Lyαline,we start by selecting nearby galaxies,normal and well-behaved kinematically,hence easy to subsequently model dynamically,and search for bright background quasars at some particular impact parameter away,ie:at the interesting radii beyond the galaxy’s HI envelope and up to about50α?1.We then observe these quasars with HST,?rst to attempt to detect a Lyαline arising from the extended galaxy’s disk,and then to use this Lyαline velocity to probe the outer dynamics of the galaxy.

Our study does not aim at elucidating the overall nature of all Lyαforest lines(other studies are better designed for this,by surveying all lines along several QSO sightlines and getting numerous spectra of galaxies in the surrounding?elds eg.Penton et al.2002,Morris et al.2002).Indeed,while it is now generally accepted that most metal-line absorption systems found in QSO’s spectra are associated with gaseous galaxy halos,the situation for the Lyαabsorption systems has been long under debate.Some studies claim that(at least the stronger)Lyαlines are associated to extended halos of galaxies,while most believe that the majority of the lines occur in the intergalactic medium,tracing the’cosmic web’(cf. van Gorkom et al.1996),this intricate network of?laments and sheets of gas predicted by hydrodynamical simulations(eg.Dav′e et al.1999).Some convincing arguments of the latter are the fact that several Lyαlines have been detected in voids(McLin et al.2002),also con?rmed by deep HI observations that would have detected dwarf galaxies and other low surface brigthness galaxies(Shull et al.1998).Also observations of double QSOs sightlines ?nd Lyαlines in common in both spectra on scales of typically half a Mpc(Dinshaw et al.1997,1998).Here we are testing the simple conjecture that gaseous galactic disks extend further beyond that which can be probed in emission in HI,by searching for a corresponding Lyαline.More importantly,a successful detection,can be used as a dynamical probe of the outer halo of the galaxy.

In Section2we explain the selection of our targets,section3describes the observations (HST and radio),then section4discuss the results of matching the Lyαvelocities with the galaxies’rotation curves and the implications.

2.Selection of Targets

Our list of QSO-galaxy pairs suitable for our purpose was compiled by cross-correlating all646quasars with V≤17.0in the V′e ron&V′e ron catalogue6th edition(1993),with the HI Catalog of Galaxies(Hutchmeier&Richter1989).This magnitude limit was imposed to make sure that the background QSO observations would stay within a reasonable amount of time to be feasible with HST.Our criteria for selection were:

i)the projected distance between the QSO and the galaxy was less than roughly10 times the optical diameter(D25)of the galaxy.This was to?nd QSOs in the interesting region beyond the galaxy’s HI emission extent but where the column density of neutral gas would still be high enough to be detected in absorption(assuming that galaxies have extended gaseous disks out to large radii as suggested by eg.Chen et al.2001).

ii)the galaxy systemic velocity was≥550km s?1.This ensured that the associated Lyαdetection stayed clear from the Geocoronal Lyman-αemission at1216?A(from the Earth’s exosphere).Moreover this also ensured that the Lyαdetection’s velocity would not fall in the range covered by the damped Lyαwing of our Galaxy,which can extend to?1220?A towards some sightlines,depending on the total HI column density present in that direction.If a galaxy’s systemic velocity is too low,any associated line would get lost in the wing of the Galactic damped line,where the continuum against which to detect this absorption line is seriously depleted.

iii)the galaxy was not interacting and was relatively isolated.This means that an observed Lyαline would be fairly unambigously assigned to that object,ie:QSO-galaxy pairs in the middle of clusters,such as for3C273,were discarded(but one target,NGC5033, was later found to be surrounded by several dwarf galaxies,see Section4.1).

iv)the galaxy’s optical diameter was at least≥1′so that a detailed kinematical study, using HI rotation curves,is feasible(since the HI radio beams will be in the best cases about a dozen of arcsecs).In some cases the rotation curves were already available in the literature.For the same reason the galaxy also had to appear“well-behaved”,with no obvious distortions or morphological asymmetries–in other words as normal as possible.

We observed a sample of9QSO-galaxy pairs with HST,chosen to cover a range of morphological types(Sa to Sd),with a range of magnitudes?20

chosen for our sample to investigate these possible trends.Table2lists the properties of our selected target galaxies.Note that the impact parameters of the galaxy-QSOs are based on distances estimated using H0=75km/s/Mpc.In the case of NGC2841there is a Cepheid distance of14.1±1.5Mpc(Macri et al.2001).Its velocity simply estimated with H0=75 would give a distance of8.5Mpc,which is only60%of this’true’distance.Hence this gives an idea of the possible large uncertainties in these impact parameters estimates.

3.Observations and Reductions

3.1.HST Observations of QSOs

Spectroscopy of our9target QSOs was obtained with the HST GHRS through the Small Science Aperture(SSA)with the G140L grating,as well as with the HST STIS/FUV-MAMA through the52X0.1aperture with the G140L and G140M gratings,as listed in Table1.This Table also gives details of the observations(the HST dataset?lenames,date of the observations)and the total integration times of the spectra.Since the QSOs have a range of?uxes,the integrations were set such as to result in a3σlimiting equivalent width of at least0.3?A,or in the case of the STIS data,to?ll completely the one orbit necessary (this3σlimit being in almost all cases achievable in less than one orbit).

The preliminary GHRS data reduction was carried out with the standard CALHRS soft-ware using the?nal GHRS reference?les,and further reduction and analysis were performed with the IRAF/STSDAS package.To fully sample the PSF,quarter-diode substepping was employed,producing four spectra per exposure.With this mode6%of the time is spent measuring the background with the science diodes.The wavelength shifts between these di?erent groups,and then between the di?erent exposures,were determined to align all the spectra before combining them and merging the wavelength and?ux information.With the G140L grating the dispersion is0.57?A per diode,corresponding to a velocity resolution of about140km s?1at1200?A.The default wavelength scale is expected to have a maximum rms of55m?A for G140L.However,zero-point shifts can be signi?cant:even though we used the small aperture which will limit the e?ect of the uncertainty in the position of the target within the aperture,thermal e?ects in the GHRS as well as geomagnetic e?ects are a large source of wavelength error(see GHRS Instrument Handbook).The wavelength accuracy achievable is about30km s?1,even when a wavelength calibration exposure is obtained just before the science exposure.For this reason these zero-points were corrected by assuming that low-ionization Galactic interstellar lines lie at the same velocity as the observed domi-nant component of the Galactic HI along these sightlines.The strongest Galactic lines were used such as Si IIIλ1206.5,Si IIλ1260.4and CIIλ1334.5.The Galactic HI LSR velocity

measurements were taken from the Leiden/Dwingeloo survey(Hartmann&Burton1997).

For the STIS observations,the G140M centered at1222?A provides a resolution of 20km s?1(with a pixel size of0.05?A)and wavelength coverage from1195to1249?A. In addition short G140L observations were obtained for the3QSOs at higher redshifts (PG1049-005,PKS1103-006,and PG1259+593).This was to make sure that any absorption feature detected at1218-1222?A(where our Lyαlines are expected)is not in fact a Lyβline associated with some Lyαline at higher redshift along the sightline.The G140L therefore provided us with a spectrum over a larger wavelength range(roughly1130to1720?A)to check on this possibility.The standard CALSTIS procedures were followed to?at?eld the individual spectra,extract them and then wavelength-calibrate and?ux-calibrate them. The MAMA spectroscopic accuracy is expected to be about0.2pixel when using the narrow slit(<3km s?1with G140M),but is ill-de?ned in practice.Hence the zero-points were corrected the same way as for the GHRS data,by shifting Galactic lines in the spectra to the main Galactic HI LSR velocity.In this case the Galactic lines used were Si IIIλ1206.5 and NIλ1199.55,λ1200.22,λ1200.71when suitable.For the Galactic HI velocities,several sightlines had higher resolution HI Galactic spectra from E?elsberg(Wakker et al.2001, 9’.1beam),and for the rest the measurements were extracted from the Leiden/Dwingeloo survey(Hartmann&Burton1997,36’beam),or from NRAO43m data(Lockman&Savage 1995,21’beam).Care was taken with galactic features at non-LSR velocities due to High-Velocity Clouds(HVCs)present in some of our sightlines.For example the MRK876sightline crosses the region of Complex C,a prominent HVC covering10%of the northern sky,and consequently the Galactic and Complex C Si III line are blended in the spectrum(Gibson et al.2001).Our?nal shifts applied to the spectra di?ered from the original calibration by0.8 km s?1up to11.6km s?1at most.Finally,after continuum?tting and normalization with a low-order polynomial,wavelengths and equivalent widths were measured,and Voigt pro?les were?tted to the observed absorption lines.These pro?le?ts are depicted in Figure3.In the case of PG1309+355,slightly better residuals were obtained if?tting3subcomponents to the line,and similarly for PG0804+761with2subcomponents.For sightlines with non-detections,equivalent width limits were calculated following the equations of Ebbets(1995).

Lyαabsorption lines were successfully detected for5of our QSO-galaxy targets(illus-trated in Figure1).Figure2shows the(unbinned)spectra with the detections,as well as the4spectra with non-detections.Table2lists the detections,and their corresponding velocities and equivalent widths.In many cases other Lyαlines were also detected along the same sightlines at other various redshifts,and do not necessarily seem to be associated with any nearby galaxy.These will be discussed more fully in a forthcoming paper.In all cases the velocities of our detections agreed within errors with those in the literature when available,for example from higher resolution FUSE data detecting the Lyβcounterparts of

some of our lines.For PG0804+761our line of interest at V Lyα=1570km s?1has not been

previously reported,but a higher redshift line in the spectrum which we detect at V LSR=5561

±8km s?1has been reported by Shull et al.(2000)at V LSR=5565km s?1and by Richter et al.(2001)at V LSR=5553km s?1(from a FUSE Lyβline).For MRK876Shull et al.(2000)

report a V LSR=958km s?1(no errors quoted)for which we have V LSR=950±5km s?1.

For the equivalent widths,a large part of the uncertainties come from the continuum

?tting,especially since some of the lines are sitting on the edge of the Galaxy’s Lyαdamped

wing.Hence the errors as presented in Table2are the sums in quadrature of the uncertainties

(1σ)from photon noise and the estimated errors from di?erent reasonable placements of the

continuum?t.The continuum Signal-to-Noise per resolution element in our spectra in the

region of the expected or detected absorption ranges from2.2to12,since our target QSOs

have a wide range of?uxes(the lowest S/N of2.2is for PKS1103-009which had a detected

?ux of only3/5of the value estimated from IUE data).

3.2.HI Observations and rotation curves

To compare the?ve detections of Lyαabsorptions in spectra of background QSOs

with the associated galaxy’s kinematics we needed its velocity?eld and rotation curve.

For NGC5033and UGC8146these were available in the litterature(Begeman1987;Rhee

&van Albada1996).For the other3galaxies we carried out Very Large Array(VLA)

HI observations,for which the observational parameters are summarized in Table3.The

correlator was set to a3.125MHz bandwidth with128channels,for a channel separation of

5.2km s?1.The calibration and reductions were performed with the NRAO package AIPS,

following standard procedures.The absolute?ux calibration was determined by observing

the standard source1331+305.After applying calibration and bandpass corrections to the

uv databases,the continuum emission was subtracted in the visibility domain using channels free of line emission.Several sets of maps were produced for each galaxy,one with uniform weighting preserving the best resolution,and a few with natural weigthing smoothed to various larger beams.These sets of maps were CLEANed well into the noise by monitoring the total cleaned?ux as a function of the total number of CLEAN components recovered, and?nally were restored with a circular symmetric Gaussian beam.These maps were then corrected for the beam response of the antennae to rectify for attenuation away from the center of the primary beam.No HI emission was detected from other galaxies within the primary beam and through the bandwidth observed other than the intended source.

Moment maps were obtained from each datacube using Hanning smoothing in velocity

and Gaussian smoothing spatially,to produce integrated total HI column density maps,

intensity-weighted velocity maps,and velocity dispersion maps.HI rotation curves were obtained by?tting a tilted-ring model to the velocity?elds(Begeman1987,C?o t′e et al.2000), and are given in Table4.In each case the rotation curves are slowly rising and just barely reach the?at part at the last measured points.The errors in velocity were calculated from half the di?erence between the velocities on each side(receding and approaching)or from the formal errors given by the least-squares?ts,whichever were the highest.The rotation curves were derived with the systemic velocities and orientation parameters(position angle and inclination)set to the values shown in Table3.The derived systemic velocities agree extremely well with the RC3values,within1km s?1.The orientation parameters as well agree within a few degrees with those derived optically(from the RC3),which show that these galaxies do not have strong warps in their outer HI gaseous envelopes.The HI distributions and HI velocity?elds are shown in Figure4,and the gas suface density pro?les in Figure5, for which the HI surface density values were scaled by4/3to account for the presence of helium.Although the three surface density pro?les di?er greatly,they are all within the range of what is commonly detected in late-type spirals.

4.Results

4.1.Lyαdetections

Figure2show the5Lyαabsorption detections amongst our9target QSOs,and Table2 gives their details.The target galaxy-QSOs which give rise successfully to a Lyαdetections have impact parameters from55kpc to169h?175kpc,and the detections correspond to HI column densities ranging from log N HI=13.0to13.9cm?2.PG1309+355-NGC5033with an impact parameter of276h?175kpc,also give rise to a detection,however in this case it was later found that NGC5033is part of a small loose group of galaxies and is surrounded by a swarm of dwarf galaxies,some of which are closer to the QSO sightline than is NGC5033(eg., UGC8261,UGC8323,UGC8314);and it is hence not possible to attribute the absorption detection to NGC5033alone.We will return to this case later on.

In each case the Lyαline velocity matches extremely well the systemic center-of-mass velocities of the galaxies.In particular for PG1259+593and MRK876their Lyαabsorption lines correspond to velocities of679and935km s?1(respectively),which are the lowest redshift Lyαlines ever detected so far in association with nearby galaxies.Presumably closer galaxies,e.g.M31,could produce Lyαlines of even lower redshift but they would be impractical to detect because of the damped wing of the Milky Way Galaxy absorbing away all the continuum?ux.In fact in Figure2,in all our spectra,the slope of the Galaxy’s damped wing is clearly seen,ie:the Lyαdetections are sitting inside the range covered by

the Galaxy’s damped wing which extends to at least～1220?A,sometimes1222?A.

As for the Lyαnon-detections,they occur for galaxy-QSO separations ranging from 162to387h?175kpc.Their3σlimiting equivalent width is in each case above the level needed to detect an absorption line even weaker than the ones detected in the other?ve spectra.In terms of HI column density limits it corresponds to a3σdetection limit around log N HI=13.1cm?2on average.This at?rst sight thus appears to con?rm the?ndings of several studies of moderately low redshift galaxy surveys associated with absorbers,which seem to point to most galaxies being surrounded by tenuous gas out to～240h?175kpc.Chen et al.(1998)and(2001),in a continuation of the work of Lanzetta et al.(1995),?nd for34 galaxies and absorbers pairs at z=0.07to0.89with impact parametersρfrom roughly16to 233h?175kpc,a near unity covering factor for tenuous gas halos around typical L?galaxies out to a radius of～240h?175kpc.Furthermore Chen et al.(1998)found that the absorbing gas equivalent width depends on the galaxy-QSO impact parameter as well as the galaxy B-band luminosity,which if true would greatly strengthen the case for a direct association between the absorber and its nearest galaxy.Meanwhile Bowen et al.(1996)found that for 38galaxies at z=0to0.08lying at<400h?175kpc from a sightline of a bright QSO observable with FOS,for lines with equivalent widths>0.3?A the covering factor is44%between67to 400h?175kpc.Recently Bowen et al.(2002)detected Lyαlines in the outer regions of all eight nearby galaxies probed,with impact parameters up to265h?175kpc,down to W>0.1?A.Our results concord with these studies.All of our detections occur at impact parameter<180 h?175kpc from the nearest galaxy,and only one of our non-detections occurs forρ<180h?175 kpc(PKS1103-006-NGC3521atρ=162h?175kpc).Note however that there is considerable uncertainty in the values ofρdue to the distance dependence(see above).All these results seem very suggestive of a link between the detected absorbers and their neighboring galaxies. But one needs to look into the detailed kinematical match between the Lyαabsorption line and the kinematics of the inner galaxy to probe more directly any direct link between an extended gaseous disk or halo of the galaxy and the absorber’s velocity.

4.2.Matching the galaxies’kinematics with the absorbers

We will try to compare here the velocity of the QSO Lyαsystem,with that of the associated galaxy.For4out of5detections,the associated galaxy is con?rmed to be isolated, hence the absorber can be unambiguously matched to this galaxy,assuming it is indeed due to a galaxy.For3of these galaxies,UGC4238,UGC7697and NGC6140,we obtained the HI rotation curves(section3).The4th one,UGC8146,has been observed by the Westerbork Synthesis Radio Telescope and its rotation curve was extracted from Rhee&van Albada

(1996).

To compare the inner galaxy dynamics with the velocity measured by the Lyαline,we will assume that the line does indeed arise in the extended gaseous disk of the galaxy and see how well it matches the velocities of the HI rotation curve in that case.The observed radial velocity of the line,V obs,is related to the corresponding rotation velocity V rot in the disk of the galaxy by:

V obs=V sys+V rot sin(i)cos(θ)(1) where V sys is the systemic velocity of the galaxy,i is its inclination,and

X

cos(θ)=

X2+Y2sec2(i)(3) R is the radius in the plane of the galaxy at which the measurement lies,in other words,the deprojected impact parameter of the QSO(a?gure demonstrating these formulae is provided in Kerr&de Vaucouleurs1955,in which however the inclination angle is de?ned as i=0for an edge-on galaxy contrary to the modern convention).For the orientation parameters of our galaxies we have used those derived from the?ts to their HI velocity?elds.

Figure6shows the resulting rotation curves.The inner points show the velocities obtained from the HI velocity?elds,and the single outer point is from the Lyαdetection. The plotted curves are simply the best?ts CDM models(Navarro,Frenk&White1996)to the inner rotation curve,and serve to guide the eyes to what velocities might be expected in these outer parts(note that such CDM curves are actually bad?ts to observed rotation curves in the inner parts,see,e.g.C?o t′e et al.2000,but here we just need them as rough approximations for the outer parts).The rotation curves in every case just reach the?at part at the very last measured point(s)(see Table4).Each case is discussed separately below.

4.2.1.NGC6140

NGC6140is the only galaxy for which the Lyαvelocity could be reasonably reconciled with the value expected if indeed arising from an extended gaseous corotating disk.Although the Lyαline velocity is much lower than the maximum rotation velocity V max of the inner rotation curve,or than the velocity expected from CDM models at that radius,there are some ways to make it consistent with a disk velocity at that radius.For example a strong warp in

the orientation parameters of the galaxy in the outer parts would change the deprojection factors and hence the calculated Lyαrotation velocity could rise to match the expected value.The present Lyαvelocity was calculated using the HI orientation parameters.One would need a warp as large as about40?in inclination,or alternatively of22?in inclination and-31?in position angle,to bring the velocity in line with the disk expected one.Most galaxies are observed to be warped in their outer parts,but such strong warps are rare for isolated galaxies.But although unusually large,one cannot a priori dismiss the possibility of such a warp in NGC6140.Another possibility to consider is if the disk,and the dark matter halo as well,of NGC6140are truncated-for whatever reasons-just outside the radius of the last measured point in HI.In this case the velocities in the outer parts should follow a keplerian fall-o?,and the velocity expected at the radius of the Lyαvelocity would fall to about46.2km s?1,close to the measured V Lyα=36.2±5km s?1.Finally another possibility is that the velocity measured is not due to gas actually in the disk plane,but from material at a certain z height in a thick disk or halo.Assuming a thick rotating disk in which the circular velocities decrease rapidly as a function of scale height,v(z)=v d e?|z|/h,where v d is the velocity in the disk midplane and h is a velocity scale height,then one can easily recover from the model a lower velocity like the one observed here by choosing an appropriate value of h.Except in the case of an in?nitely large h where the thick disk is corotating cylindrically, the velocities at some z distance will be much lower than the midplane one This is observed in NGC891for example,in which some HI halo gas extending up to5kpc from the plane is seen to rotate25to100km s?1more slowly than the gas in the plane(Swaters,Sancisi &van der Hulst1997).Hence the observed Lyαvelocity of NGC6140would not be at all unphysical but would simply re?ect the presence of a rotating thick disk(with detectable gas only at higher z height,and none in the plane of the disk).For the moment,with only one sightline velocity at large radius,it is not possible to discriminate between these various possibilities and con?rm any of them.

4.2.2.UGC4238and UGC8146

The situation for UGC4238and UGC8146is di?erent.In these two cases,assuming planar kinematics,the measured Lyαvelocity corresponds to a circular velocity actually larger than the expected CDM one or even the V max reached by the inner rotation curve.

A very signi?cant increase of rotation velocity with radius would be required to explain the observed velocity.However one can again invoke warps to make the observed velocity consistent with the extrapolation of the inner disk rotation.In fact in these two cases, because of the particular orientation parameters of the galaxies and their angle with respect to their associated quasars’sightline,one would need only mild warps(of the order of10?in

the suitable direction)to make the match.Consequently one can still not dismiss a priori the possibility that the absorptions indeed arise from co-rotating gaseous extensions of the inner disks,albeit non-planar motions.

4.2.3.UGC7697

The QSO,TON1542,is situated at the South-West of the galaxy;the observed velocity (V obs=2557km s?1)is greater than the systemic velocity(V sys=2536);yet the galaxy’s approaching side is towards the West,meaning the velocities should all be smaller than V sys.The observed velocity from the absorption line is counter-rotating with respect to the disk velocities.And the observed velocities and geometry of the case of UGC7697are such that warps cannot provide consistency with an extended gas disk.Unusually large warps would be required to reverse the inclination of the disk on the sky so that counter-rotation is observed,and such twisted rotating disks would be unlikely to be stable(with the exception of nearly face-on galaxies where the reversal of the inclination would be easier to achieve; see for example Cohen1979or Appleton,Foster&Davies1986,where such a possibility is discussed to explain the apparent velocity reversals in IC10and M51).Counter-rotation at very large radii has been observed in HI in a few galaxies,but those are always galaxies interacting with a nearby dwarf(for example NGC4449,Hunter et al.1998)or which also harbour inner counter-rotation and hence easily stand out morphologically(like NGC4826, the’Evil-Eye’galaxy,Braun et al.1994).Neither of these cases apply here for any of the galaxies in our sample.In the case of UGC7697no amount of disk thickening,or warps could explain the discrepancy(unless abnormally large).There are simply no physical way to produce such a velocity with an extended corotating disk.This is sobering because UGC7697is one of the galaxies for which the QSO is at the smallest impact parameter,and yet the absorption’s velocity does not match.It is also interesting to note from Figure1that for UGC7697the QSO lies close to the projected optical major axis in angle(compared to the other galaxies).If the gas has a higher column density in the disk than in the halo we should have expected a clear detection of the rotating HI disk of UGC7697,if it does reach out to this radius at the N HI=1013cm?2level.

Note that some have invoked the existence of very low-surface brightness galaxies or dwarf galaxies,undetected in the optical,which could lie closer to the QSO sightline than the apparently nearest galaxy and from which the Lyαline would originate.In the case of UGC7697this is very unlikely since we also acquired deep HI pointings with the VLA on all of our QSOs?elds and should have detected such galaxies,down to a few106M⊙(to be presented in a forthcoming paper).

4.2.4.From the literature:NGC988and NGC3942

Our conclusion that the Lyαabsorptions cannot arise in simple extended disks are con?rmed by two other galaxies associated with Lyαabsorbers taken from the literature, for which similar results are found.Bowen,Pettini,and Blades(2002)targeted a sample of eight nearby galaxies near the sightlines of QSOs and AGNs.Most of their galaxies are not isolated(contrasting with the careful selection criteria of our sample),but are part of binary pairs or small groups(their sample was produced by cross-correlating the RC3 with the Veron-Cetty&Veron(1996)catalog,and choosing galaxies with>1300km s?1, and with impact parameters to QSOs of less than200h?1100kpc).However two galaxies, NGC988and NGC3942are reasonably isolated,at least on the scale of a few hundreds of kpc.Their projected separations from their associated QSOs are211and123h?175kpc respectively,and no other galaxies are known around a diameter of400kpc from these QSO sightlines.Unfortunately no rotation curves,either optical(in Hα)or HI,are available for these two galaxies.But for the sake of comparing the inner galaxy’s kinematics with the Lyαabsorption velocity,we can use NGC988and NGC3942’s magnitude to derive approximate rotation curves,using the‘universal rotation curve’of Persic&Salucci(1996)(where they obtained,based on a sample of1100rotation curves,a relation between the shape and amplitude of a rotation curve,and the luminosity of the galaxy).We will see below that these approximations are more than satisfactory to be able to draw our conclusions.The Lyαline velocities observed in the spectra of MRK1048and PG1149-110respectively are taken from Bowen et al.(2002).One last important piece of information needed to compare the inner and outer velocities is that the sense of rotation of the galaxy must be known,ie. we must determine if the QSO lies behind the approaching or the receding side of the galaxy (otherwise it is not known if the velocity di?erence is due to corotation or counter-rotation). This might be di?cult to establish without a proper2D velocity?eld for these two galaxies. Fortunately NGC988and NGC3942are reasonably nearby and extended in angular size, and hence their HI envelope should be at least a few arcmins in diameter.In that case it is possible to detect the change in shape of the HI global pro?le at di?erent positions around the galaxy in the HIPASS scans(HIPASS is the All-Southern-Sky HI survey performed with the Parkes Multibeam receiver and available on-line,Barnes et al.2001).By retrieving the HI pro?les on each side of the galaxy(the pointings in the on-line catalog are separated by roughly8arcmins from each other),it is possible to follow the change from a double-peak pro?le for NGC988(with a systemic velocity of1504km s?1)to a single peak roughly at1400 km s?1at the East to one around1600km s?1at the West,and hence determine that for NGC988the approaching side is at the East and the receding one at the West.Similarly for NGC3942the approaching side is seen to be in the South-East and the receding one in the NorthWest.With this information one can then plot the rotation curves of Figure7.They

con?rm the?ndings on our galaxies above.Because for NGC988the velocity di?erence between the Lyαabsorption line and the systemic velocity of the galaxy is already quite large,this translates into a rotation velocity(with the appropriate deprojections)which is ridiculously too elevated(～1192km s?1),and no amount of warping,no matter how severe, can bring this velocity down to a value close to V max.For NGC3942the calculated rotation velocity is also inadequate,as we?nd here another case of counter-rotation.Again NGC3942 has a relatively small impact parameter to the Lyαline,compared to those in our sample, with the projected distance corresponding to147h?175kpc,and yet already at that radius we do not detect any longer the extended corotating gaseous disk of the galaxy.

4.3.The nature of the Lyαdetections

Could it be that somehow,although not in a corotating disk or halo,this detected gas is still associated to the galaxy?After all the Milky Way is known to be surrounded by High-Velocity-Clouds,which can have velocities above,or below,the Galaxy’s rotation velocity by several hundred km s?1(see,e.g.Wakker1991).Following strong supernovae events some ejected gas might hide into a hot phase until eventually it cools down and could then be detected to low column densities in our sightlines at very large radii.Multiple supernovae remnants can drive a superbubble evolving quickly into a blowout,leaving a hole in the galactic disk(eg.MacLow&McCray1988).Some gas can even be accelerated beyond the escape velocity and be’blown-away’,completely unbound from the galactic potential (de Young&Heckman1994).For small dwarf galaxies,for which it is easier to escape the potential,it might be possible to generate large(100kpc size)gaseous halos with supernovae-driven winds(Nath&Trentham1997).For larger galaxies it is expected that there should be a local circulation of gas(to a few scalelengths above the disk)via a fountain-type?ow (Shapiro&Field1976).However it might be unlikely though to blow gas out of a more normal galaxy(closer to L?)to distances of more than100kpc,corresponding to factors of up to7.5times the diameter of the galaxy-as is the case here for NGC6140.

Another possibility is that we are intercepting satellites objects(very small galaxies or clouds of gas)orbiting around the primary galaxy.This would explain the counter-rotating velocities,as satellite objects can have retrograde as well as prograde orbits.In fact in the study of the supermassive disk galaxy NGC5084orbited by a record number of9satellite dwarf galaxies(Carignan et al.1997),the large majority of the satellite objects(7out of9)are on retrograde orbits.The problem with this explanation though is the overly large covering factor of the detected gas for impact parameters<160kpc.In the Bowen et al.(2002) study they?nd a detection for all QSOs at impact parameters<265h?175kpc(down to W>

0.11?A),and in our case all QSOs at<136h?175kpc yield a detection.It would thus be very unlikely that by chance the sightlines always intercept one of the satellites,considering especially the range of orientation parameters of the targets.Moreover these satellite objects would have to have very unusual properties compared to other dwarf galaxies,since we have deep VLA HI pointings of all our?elds in which we would have detected any objects above about106M⊙(to be presented elsewhere).

Another important clue in constraining the nature of the detected Lyαabsorbers is the inspection of the lines’equivalent widths.A strong argument in favour of the extended galactic disks’origin of the Lyαlines has been the apparent anti-correlation between equiv-alent width and impact parameter for the lines,the absorption being stronger the closer it is to the galaxy(Lanzetta et al.1995).The Chen et al.(1998)study?nd also a dependence on the luminosity of the galaxy,of the form:

log(N

10kpc

)+2.19log(

L B

density of M B

In Figure8is plotted similarly our Lαlines versus the estimated volume density of galaxies around our targets.Following Bowen et al.(2002)we summed all components of Lyαabsorption within+500km s?1and-500km s?1from the main Lyαline.Only in one case(PG0804+761)was there another Lyαabsorber to add up within that range.We considered similarly only galaxies with M lim

Our data agree very well with the Bowen et al.(2002)result,within errors(our errors in √

n are simply

a B lim=15.5for our sample objects,and in a smaller cylinder of0.5h?1Mpc radius.Again the relation holds very well,although we are dealing with even smaller number statistics.

It thus appear that there is a relationship between the Lyαcolumn density along a sightline and the surrounding volume density of galaxies.This makes sense if the absorbers are simply part of the cosmic web.The galaxies have condensed in the densest parts of this network of?laments and sheets of gas,and hence the Lyαdetections will be denser when crossing a web?lament/sheet rich in galaxies.The Lyαabsorbers are only detected within about<170h?175kpc down to our limiting equivalent widths in the neighbourhood of galaxies because that is where the gas has higher column density in the?lament,in the dense region from which the galaxy has condensed.On a larger scale,the Lyαline will be stronger when crossing the core of a?lament,or a busy’intersection’of?laments of the web,where one?nds a higher density of galaxy,on a scale of2h?1Mpc radius.That the relationship seems to still hold on the smaller scale of0.5h?1Mpc radius when considering the density of lower luminosity galaxies(Figure9)is perhaps not surprising,as small groups of galaxies(like the agglomeration around PG1309+355)tend to be found on the periphery of larger clusters while most of our other targets are probably in semi-void regions(since galaxies were purposely selected to be isolated for the aim of this project).It is not obvious what should be the relevant scale to calculate the surrounding galaxy density.In simulations of the cosmic web,the?laments come in various thickness although are de?nitly of the order of the Mpc,down to the detectable column densities as here(Miralda-Escud′e et al.1996, Dav′e et al.1999).Observations of double QSOs sightlines also?nd that,by looking at Lyαlines in common in both spectra,the typical scale is around0.5Mpc(Dinshaw et al.1997, 1998).

It is interesting to look also at the Doppler b parameters from the Voigt pro?le?ts and compared them to those obtained by Bowen et al.(2002)(keeping in mind that some b values are uncertain because of the W?b degeneracy for saturated lines).In most of their sightlines several resolved Lyαlines were added up(within their+500and-500km s?1limit)to add up to the total equivalent widths plotted in Figure8.In constrast,for most of our sample, the total equivalent widths come mostly from a single line.PG0804+761is an exception, for which two lines were added,and also because the main line associated with the galaxy (ie.which matches more closely in velocity)is better?tted by two pro?les rather than one.Similarly for PG1309+355,the pro?le,which has the highest equivalent width of all,is very broad and show several features,and the?t is considerably improved by?tting3voigt pro?les rather than a single one.Interestingly the trend of Figure8holds well whether one is considering the addition of several narrow lines(typically b<50km s?1)in the case of the Bowen et al.(2002)sample,or the denser,wider single b lines from our sample.One cannot exclude that our single lines are actually unresolved groups of narrower lines.If not there

might be a real physical di?erence in the density and temperature of the cosmic web gas depending on the environment,since our galaxies were mostly selected to be isolated,while the Bowen et al.(2002)ones are part of pairs or small groups.The Bowen et al.(2002)lines are also at redshifts on average twice as distant than for our sample.While some evolution with redshift is expected for the density of the cosmic web,since at lower redshift more of the gas will have condensed along the?laments(Dav′e et al.1999),the two samples discussed here probably do not cover a wide enough range in redshift to see this.Our b values go up to about150km s?1,unusually large for Lyαforest absorption lines,although a few of the Bowen et al.(2002)sample do reach similar values.If the lines are indeed composed of only a single component,and assuming that the linewidth is purely due to the gas kinetic temperature(in which case b=

velocities with the predicted ones.Worse,in some cases the Lyαline velocity indicates in fact counter-rotation with respect to the inner disk rotation.

In light of these results it appears that there is no detectable gas,down to levels of about1013cm?2,corotating in an extended gaseous disk at radii>35α?1.The cosmic web is the most likely origin for the detected Lyαlines.The observed equivalent widths of the lines are consistent with this picture.Indeed the equivalent widths are correlated with the local volume density of galaxies around the sightline.This makes sense if the Lyαlines arise from the cosmic web,which is denser in regions of higher volume density of galaxies (since the galaxies have formed by condensating in the denser parts of the network).This correlation would be di?cult to explain if the Lyαlines arised from halos or extended disks of the most nearby galaxy.One could argue that the equivalent widths should be larger for sighlines close to larger galaxies,which tend to be found in regions of higher galaxy volume density,which could then explain the trend observed.However if this were the case then one would observe presumably an even stronger correlation between the equivalent widths and the luminosity of the nearby galaxy,and although this was reported to be the case by Chen et al.(1998)it is now clearly contested by the results of Bowen et al.(2002),as well as in our sample for which no correlation is found between equivalent widths and luminosities.

Note that these results do not necessarily imply that the dark matter haloes of these galaxies do not exist at the radii probed by our QSO sightlines.It simply means that there is no longer some detectable gas in rotation in an extended gas disk at these radii,and that the Lyαlines detected are due to foreground or background cosmic web gas surrounding the galaxy.In fact weak lensing studies seem to indicate that indeed the dark matter halo extend very far out,typically>300h?175kpc for a L?galaxy(eg.the weak-lensing studies such as Smith et al.2001).But there is no gas to trace its dynamics out there,at least down to our limiting column densities.HI as traced by background QSOs is therefore not a useful tracer of galactic potential in the far outer regions of a～200kpc halo.Only weak lensing,and perhaps Hαin recombination from the extended ionized disk(Bland-Hawthorn et al.1997) are hopeful tracers of dynamics at such radii.These QSOs turn out however to be extremely useful to probe the phases of the cosmic web gas.Many more sightlines will be required though before one can attempt to understand the cosmic gas distribution and density,as well as its evolution with redshift.The planned HST COS spectrograph would have allowed to probe the sightlines of fainter QSOs which would greatly increase the available sample, and hopefully the decision regarding HST can be reversed in the future.Eventually the next generation of sensitive giant radio telescopes as the CLAR(C?o t′e et al.2002)and eventually the SKA,will be able to survey e?ciently large areas of the sky down to colum densities as deep as1016cm?2,and hence trace directly in emission the structure of such low column density gas in the cosmic web.

英语单词惯用法集锦解析

英语单词惯用法集锦 习惯接动词不定式的动词（V to inf) adore(vi极喜欢) dread （vt.不愿做，厌恶）plan 计划 afford（+to,vt有条件，能承担）endeavour （vt，竭力做到，试图或力图）prefer（vt.宁可；宁愿(选择)；更喜欢）agree 同意endure(忍受.cannot ~ to) prepare准备 aim (vi[口语]打算：) engage (vi.保证，担保；) presume(vt.冒昧；敢于[用于第一人称时为客套话]：) appear (vi.似乎；显得) essay(vt.尝试，试图) pretend(vt.自命；自称；敢于；妄为) apply （申请）expect（期望，希望）proceed（开始，着手，）arrange （vi.做安排，(事先)筹划）fail （vt.未做…；疏忽)promise(许诺，保证做 ask （要求）forget （vt. 忘记）purpose （vt.决心，打算） beg （vt.正式场合的礼貌用语]请(原谅)，请(允许)：I beg to differ.恕我不能赞同）guarantee（保证，担保）refuse（拒绝）bear 承受，忍受hate（[口语]不喜欢；不愿意；）regret （vt. 抱歉；遗憾）begin help （有助于，促进）remember（记住） bother （vi.通常用于否定句]麻烦，费心）hesitate（vi.犹豫；有疑虑，不愿）scheme（策划做）care （vt.想要；希望；欲望[后接不定式，常用于否定、疑问及条件句中]）hope （vt.希望，盼望，期待）seek（vt.谋求，图谋[后接不定式]） cease （停止; 不再(做某事)[正式] intend （打算；想要）seem（似乎，好像[后接不定式或从句]；觉得像是，以为[ choose （意愿；选定；决定）itch start开始claim （vt. 主张；断言；宣称） continue （继续）like 喜欢swear（vt.起誓保证；立誓要做(或遵守） dare （vt.敢，敢于，勇于，胆敢）long（vi.渴望；热望；极想） decline（vt.拒绝，拒不(做、进入、考虑等) manage（设法完成某事）threaten（vt.威胁，恐吓，恫吓）deign （屈尊做）mean（有意[不用进行时）trouble（vi.费心，费神；麻烦）demand（vi.要求，请求：）need （需要）try（设法做） deserve (应得) neglect (疏忽) undertake(承诺,答应，保证) desire （希望渴望）offer（表示愿意(做某事)，自愿；）venture（冒险(做某事））determine（vi.决心，决意，决定，）omit （疏忽，忘记）want 想要 die （誓死做）pine （渴望）wish （希望） 习惯接“疑问词+动词不定式”的动词（有时也包括VN wh-+to do) advise 建议explain 解释perceive 觉察，发觉 answer 答复find 得知，察觉persuade 说服，劝说；使某人相信 ask 询问，问forget 忘记phone 打电话 assure 保证guess 臆测，猜度pray 祈祷 beg 请求，恳求hear 小心聆听（法庭案件）promise 允诺 conceive 想象，设想imagine 以为，假象remember记得 consider 考虑，思考indicate 暗示remind 提醒，使想起 convince 使相信inform告知通知instruct告知，教导 see 看看，考虑，注意decide 解决，决定know 学得，得知 show 给人解释；示范；叙述；discover发现；知道learn 得知，获悉 signal以信号表示doubt 怀疑，不相信look 察看；检查；探明 strike 使想起；使突然想到；使认为suggest 提议，建议tell 显示，表明；看出，晓得；warn 警告，告诫think 想出；记忆，回忆；想出，明白wonder 纳闷，想知道 wire 打电报telegraph 打电报 习惯接动名词的动词（包括v+one’s/one+v+ing) acknowledge 认知，承认…之事实escape免除，避免omit疏忽，忽略 admit 承认，供认excuse 原谅overlook 放任，宽容，忽视adore （非正式）极为喜欢fancy 构想，幻想，想想postpone 延期，搁置 advise 劝告，建议finish完成prefer较喜欢 appreciate 为…表示感激(或感谢)forbid 不许，禁止prevent预防 avoid 逃避forget 忘记prohibit 禁止，妨碍

肺功能检查的适应证及意义复习课程

如有侵权请联系网站删除 肺功能检查适应症及临床意义 适应症: 1—外科手术前（胸部或上腹部手术，如肺切除；麻醉时间长。术前肺功能评估，了解肺通气储备容量大小，以评价肺功能对手术的承受能力及发生术后肺部合并症的危险程度，尤其年龄大于50岁、长期吸烟、既往有慢支哮喘等肺部疾病病史者）。 2 .内科疾病的诊断、鉴别、疗效评估。慢性阻塞性肺病，支气管哮喘，不明原因的慢性咳嗽，过敏性鼻炎，肺弥漫性间质性或肺泡性疾病。 3.体检。污染环境下工作的人，公司或学校等进行群体体检，用于伤害定性和赔偿检查，长期吸烟者。 6.其它。不明原因的胸闷、心悸；反复发生的支气管炎和肺炎；申经肌肉疾病；风湿性疾病的肺损伤；劳力性呼吸困难。 禁忌症： 活动性咯血；活动性肺结核；未经胸腔引流的气胸； 心血管疾病，用力呼吸测试可能会加剧心绞痛或者引起血压改变，或者最近有心肌梗塞或肺栓塞； 胸部、上腹部或者头颅的血管瘤（胸内压增高会引起破裂的危险）；近期的眼部手术，如白内障。 临床意义： 肺功能检查是临床上胸肺疾病及呼吸生理的重要检查内容。对于早期检出肺、气道病变，鉴别呼吸困难的原因，诊断病变部位，评估疾病的病情严重度及其预后， 评定药物或其它治疗方法疗效，评估肺功能对手术的耐受力或劳动强度耐受力及对危重病人的监护等，肺功能检查均是必不可少的。 1、用于检测呼吸道的通畅程度、肺容量的大小，了解通气功能损害程度，鉴别肺通气功能障碍的类型如：阻塞性、限制性、混合性通气功能障碍。是对有吸烟病史的人检测是否有CAO（慢性气流阻塞）存在的“金标准”以及诊断COPED慢性阻塞性肺疾病）的“金标准”。 2、鉴别气道梗阻的类型如胸内型、胸处型或固定型、可变型。 3、用于胸腹部外科手术前肺功能评估，了解肺通气储备容量大小，以评价肺功能对手术的承受能力及发生术后肺部合并症的危险程度。 4、支气管激发试验：用于确诊支气管哮喘。对可疑哮喘病人或以咳嗽表现为主的可疑哮喘患者进行鉴别诊断，也可以用于急、慢性支气管炎、过敏性鼻炎等疾病，了解有无气道反应性。 精品资料

感官动词和使役动词

感官动词和使役动词 默认分类2010-05-28 23:14:26 阅读46 评论0 字号：大中小订阅 使役动词，比如let make have就是3个比较重要的 have sb to do 没有这个用法的 只有have sb doing.听凭某人做某事 have sb do 让某人做某事 have sth done 让某事被完成（就是让别人做） 另外： 使役动词 1.使役动词是表示使、令、让、帮、叫等意义的不完全及物动词,主要有make(使,令), let(让), help(帮助), have(叫)等。 2.使役动词后接受词,再接原形不定词作受词补语。 He made me laugh. 他使我发笑。 I let him go. 我让他走开。 I helped him repair the car. 我帮他修理汽车。 Please have him come here. 请叫他到这里来。 3.使役动词还可以接过去分词作受词补语。 I have my hair cut every month. 我每个月理发。 4.使役动词的被动语态的受词补语用不定词,不用原形不定词。 (主)He made me laugh. 他使我笑了。 (被)I was made to laugh by him. 我被他逗笑了。 使役动词有以下用法： a. have somebody do sth让某人去做某事 ??i had him arrange for a car. b. have somebody doing sth.让某人持续做某事。 ??he had us laughing all through lunch. 注意：用于否定名时，表示“允许” i won't have you running around in the house. 我不允许你在家里到处乱跑。 ******** 小议“使役动词”的用法 1. have sb do 让某人干某事 e.g:What would you have me do? have sb/sth doing 让某人或某事处于某种状态，听任 e.g: I won't have women working in our company. The two cheats had the light burning all night long. have sth done 让别人干某事，遭受到 e.g:you 'd better have your teeth pulled out. He had his pocket picked. notes: "done"这个动作不是主语发出来的。 2.make sb do sth 让某人干某事 e.g:They made me repeat the story. What makes the grass grow?

常见动词用法

1、keep ①keep + 形容词表示“保持” Please keep quite. 请保持安静。 ②keep + 宾语+ 形容词（或介词短语）表示“把……保持在某一状态” We must do everything we can to keep the air clean. 我们必须尽一切所能保持空气清洁。 ③keep sb doing sth 表示“让某人做某事” ——只能用现在分词作宾语补足语，不能用不定式。 He kept us waiting for two hours. 他让我们等了两个小时。 He kept us to wait for two hours. (错误) ④keep on doing sth和keep doing sth 表示“继续做某事，反复做某事”，可换用。 但keep on doing 更强调动作的反复性或做事人的决心。 He keeps on phoning me, but I don’t want to talk to him. Though he failed 3 times, he kept on trying. 他老是给我打电话，但我不想同他讲话。虽然他已失败了3次，但他仍继续干下去。 keep doing sth 经常用于静态动词。 He kept lying in bed all day long. 他整天都躺在床上。 ⑤keep …from doing sth 表示“阻止，使免于” He kept them from fishing in the lake. 他不让他们在那个湖里捕鱼。 2、may not / mustn’t / needn’t / wouldn’t ①may not be 是may be的否定式，意为“可能不是，也许不是” He may be there.他可能在那里。He may not be there.他可能不在那里。 ②must 意为“必须”，mustn’t 意为“千万不可，绝对不可” 所以Must we/I ……?的否定回答要用needn’t—意为“不必” -Must we get there before 11 o’clock？ -No, we needn’t. ③wouldn’t = would not 意为“不会，不愿” I wouldn’t say no. 3、do ①do表示“做”，做某事，常指某种不具体的活动；make表示“制作”，指做出某种具体的东西。

共同但有区别责任原则

题目：共同但有区别的责任原则在实施中的困境与对策姓名：罗珠玉、戴政

共同但有区别的责任原则在实施中的困境与对策 摘要：共同但有区别的责任原则作为国际环境法的一项基本原则，该原则的要求在实践中未能得到充分尊重与落实。笔者通过对该原则实施困境及原因的分析,寻求解决该原则的可行性办法。 关键词：共同但有区别的责任原则；实施困境；可行性办法

共同责任和区别责任组成了共同但有区别责任原则。二者之间相辅相成，密不可分。一方面各国不能以任何的借口而拒绝参与环境保护问题，这是每个国家的共同责任；另一方面，基于合理性而产生的区别责任，我们在对待共同责任的同时要给予发达国家与发展中国家差别待遇。只有当我们正确的理解二者关系时才能确保该原则的正确实施。实践中，该原则面对来自不同国家的阻力。 一、共同但有区别的责任原则的实施困境 发达国家有先进的技术与雄厚的资金，在各国订立国际公约之初，对发达国家明确规定了需向发展中国家提供环保技术的援助。可公约本身并未说明具体的援助方式，使发达国家有机可趁，利用市场操作以高价的方式向发展中国家提供商业性援助。而即使存在无偿性援助，实际数据也令人心寒，发展中国家适应气候变化每年所需的资金大约在 500 亿美元，而联合国的专门基金从发达国家筹集到的资金从 90 年代初至今总计只有 670 亿美元，发达国家对发展中国家的资金援助可见一斑，这也是共同但有区别责任难以落实的一个重要原因。 在发展中国家共同但有区别的责任原则的实施也受到了挑战。发展中国家的经济水平比较落后，他们没有先进的技术支撑他们在保证解决自己温饱问题的同时兼顾环境保护，而要想解决生存问题必须以牺牲坏境为代价。传统的经济发展技术、能源技术已经不能适应现代可持续发展的要求，尤其 21 世纪对各国高新技术提出了更高的要求，在环境治理方面也不例外。现在单纯的现有技术转让已经不能满足发展中国家环境治理的需要了，发达国家需要尽可能地多与发展中国家进行技术交流与合作，让发展中国家也成为高新技术开发的参与者，掌握自主的知识产权。 最后，为应对国际环境的问题而制定的众多国际公约，足以应对坚持和实施共同但有区别的责任原则。比如《人类环境宣言》、《联合国气候变化框架公约》、《联合国海洋法公约》、《京都议定书》······这些制定与签署的国际公约，不仅构成了世界环境保护国家合作的标准，而且也未共同但有区别责任作出了各种细化的规定。 二、共同但有区别的责任原则实施中存在困难的原因 美国曾以不符合本国的国家利益为由退出《京都议定书》，而各国对其只能进行谴责，因为国家享有主权原则，有权决定自己是否愿意加入某一国际公约。

感官动词的用法

感官动词 1.see, hear, listen to, watch, notice等词，后接宾语，再接省略to的动词不定式或ing形式。前者表全过程，后者表正在进行。句中有频率词时，以上的词也常跟动词原形。 注释:省略to的动词不定式--to do是动词不定式，省略了to,剩下do，其形式和动词原形是一样的，但说法不同。 see sb do sth 看到某人做了某事 see sb doing sth 看到某人在做某事 hear sb do sth 听到某人做了某事 hear sb doing sth 听到某人在做某事 以此类推... I heard someone knocking at the door when I fell asleep. (我入睡时有人正敲门,强调当时正在敲门) I heard someone knock at the door three times. (听到有人敲门的全过程) I often watch my classmates play volleyball after school. (此处有频率词often) （了解）若以上词用于被动语态，须将省略的to还原： see sb do sth----sb be seen to do sth hear sb do sth----sb be seen to do sth 以此类推... We saw him go into the restaurant. → He was seen to go into the restaurant. I hear the boy cry every day. → The boy is heard to cry every day. 2.感官动词look, sound, smell, taste, feel可当系动词，后接形容词。 He looks angry. His explanation sounds reasonable. The cakes smell nice.

动词以及动词短语的用法(动词后加to do 还是doing)

一动词加-ing 的情况 consider, suggest/advise,look forward to, excuse/pardon admit,delay/put off,fancy avoid,miss,keep/keep on,practise deny,finish,enjoy/appreciate forbid,imagine,risk can't help,mind,allow/permit,escape 考虑建议盼原谅, 承认推迟没得想. 避免错过继续练, 否认完成就欣赏. 禁止想象才冒险, 不禁介意准逃亡. 如：建议：advise,suggest,冒险:risk,献身:devote oneself to 二动词后加doing 和加to do sth. 意思不一样的情况 ①remember doing指记住过去做过的事，remember to do指记住将来要做的事，表示“不要忘记”。 ②forget doing表示忘记过去做过的事，forget to do表示“没有想起做某事”。 ③mean doing表示“意味着做某事”，mean to do表示“打算做某事”。 ④regret doing表示对已做过的事感到后悔，regret to do表示对将要做的事表示遗憾。 ⑤stop doing表示“停止做某事”，stop to do是停止做正在做的事以便去做另外一件事，这里的to do不是stop的宾语而是stop的目的状语。 ⑥try doing表示“尝试做某事”，try to do表示“设法、试图做某事”。 ⑦go on doing表示继续做同一件事，go on to do表示做完一件事后，接下去做另外一件事。 三动词后加to do sth. afford负担得起agree同意appear似乎，显得arrange安排 ask问attempt企图beg请求begin开始 choose选择claim要求decide决定demand要求 desire愿望determine决定expect期望fail不能 forget忘记happen碰巧hate憎恨，厌恶hesitate犹豫 hope希望intend想要learn学习long渴望 love爱manage设法mean意欲，打算need需要 neglect忽视offer提供omit忽略，漏other扰乱；烦恼

论共同但有区别责任原则在我国的适用(改)

论共同但有区别责任原则在我国的适用 摘要: 文章在结合我国的具体国情的基础上,对我国进行环境污染防治过程中在环境保护法律中适用这一前沿的原则所具有的理论基础以及需要注意的问题进行了探讨。 关键词:京都议定书;共同但有区别责任原则;共同责任;区别责任 1 共同但有区别责任原则概述 共同但有区别责任原则是国际环境法中的一项基本原则。这一原则的产生主要是基于各国社会发展的历史对国际环境的影响及本国的实际承担能力。其核心思想是,在实现将大气中温室气体的浓度稳定在防止气候系统受到危险的人为干扰的水 平上这一目标过程中全球各国都负有共同的责任和义务,但是基于各国的历史发展 状况及现实承受能力,发达国家应该在这一过程中应该率先承担并且承担主要的责任。 1.1共同但有区别的责任原则主要包含以下两个基本要素： 1.1.1共同责任 共同责任的理论依据:全球的生态系统是一个不可分割的整体,环境问题具有全球性,解决全球环境问题需要所有国家的参与，每个国家都有责任。全球环保问题已经成为人类共同关注的焦点,而不只是某一个国家的国内立法问题。 共同责任的内容:许多关于环境与发展的国际文件中均有共同责任的规定。共同责任要求每个国家不论其大小、贫富等方面的区别,都对保护全球环境负有一份责任,都应当参加全球环境保护事业,都必须在保护和改善环境方面承担义务。基于共同责任,所有国家,尤其是发展中国家,都应该参与关于可持续发展的立法以及相关法律 的实施。许多现有的有关环境的国际法律文件没有发展中国家的参与。为了保护发展中国家的利益,有必要对相关文件进行修订，从而确保上述法律文件适用范围的广泛性。 1.1.2有区别的责任 有区别的责任的理论依据:有区别的责任的理论依据是公平原则。如果一个国家曾未经其他国家同意而不公平地对其进行利用而使其付出代价,那么受害国有权要

英语中感官动词的用法

英语中感官动词的用法 一、感官动词 1、感官动词(及物动词)有：see/notice/look at/watch/observe/listen to/hear/feel(Vt)/taste(Vt)/smell(Vt) 2、连缀动词(含感官不及物动词) be/get/become/feel/look/sound/smell/taste/keep/stay/seem/ appear/grow/turn/prove/remain/go/run 二、具体用法： 1、see, hear, smell, taste, feel,这五个动词均可作连系动词，后面接形容词作表语，说明主语所处的状态。其意思分别为"看/听/闻/尝/摸起来……"。除look之外，其它几个动词的主语往往是物，而不是人。 例如：These flowers smell very sweet.这些花闻起来很香。 The tomatoes feel very soft.这些西红柿摸起来很软。 2、这些动词后面也可接介词like短语，like后面常用名词。 例如：Her idea sounds like fun.她的主意听起来很有趣。 3、这五个感官动词也可作实义动词,除look(当"看起来……"讲时)只能作不及物动词外,其余四个既可作及物动词也可作不及物动词,此时作为实义动词讲时其主语一般为人。 例如:She smelt the meat.她闻了闻那块肉。 I felt in my pocket for cigarettes.我用手在口袋里摸香烟。 4、taste, smell作不及物动词时,可用于"t aste / smell + of +名词"结构,意为"有……味道/气味"。 例如:The air in the room smells of earth.房间里的空气有股泥土味。 5、它们(sound除外)可以直接作名词,与have或take构成短语。 例如：May I have a taste of the mooncakes?我可以尝一口这月饼吗？taste有品位、味道的意思。 例如：I don’t like the taste of the garlic.我不喜欢大蒜的味道。 She dresses in poor taste.她穿着没有品位。 look有外观，特色的意思，例：The place has a European look.此地具有欧洲特色。 feel有感觉，感受的意思，watch有手表，观察的意思。例：My watch is expensive.我的手表很贵。 6、其中look, sound, feel还能构成"look / sound / feel + as if +从句"结构，意为"看起来/听起来/感觉好像……"。 例如：It looks as if our class is going to win.看来我们班好像要获胜了。 7、感官动词+do与+doing的区别： see, watch, observe, notice, look at, hear, listen to, smell, taste, feel + do表示动作的完整性，真实性；+doing 表示动作的连续性，进行性。 I saw him work in the garden yesterday.昨天我看见他在花园里干活了。(强调"我看见了"

pretend三种易混淆不定式的用法

pretend三种易混淆不定式的用法 今天给大家带来了pretend三种易混淆不定式的用法，我们一起来学习吧，下面就和大家分享，来欣赏一下吧。 pretend三种易混淆不定式的用法 1. pretend to do sth .这个短语的意思是假装(将要)去做什么事情，适用于将来时态动作将来假装要去做但不一定去做的状态。 举例: If youpretend to know what you dont know，youll only make afool of yourself.不懂装懂就会闹笑话。(suri的回答) Child pretend to be mother and father in kindergarten.孩子在幼稚园里面假扮父亲和母亲(表将来)(JasoOon的回答) 2. pretend to have done sth .这个短语的意思是假装已经做过了某事，强调事情的一个完成的状态，侧重于假装的事情已经做好了。 举例:I pretend tohave seen nothing，but I cant.我假装自己没有看到任何东西，但是我做不到(侧重于一个完成时态，已经试图去假装没有看到)

she pretended to have finished the homeworkwhen she went out and played.当她出门玩的时候她假装自己已经完成了家庭作业。(假装做作业这个动作已经在出门玩之前做完了)(JasoOon的回答)以及怀陌的回答:When the teacher came in，he pretended to havefinished the homework.当老师进来的时候他假装自己已经完成家庭作业了，两者有异曲同工之妙。 3. pretendtobe doing sth 这个短语的意思是假装正在做某事，强调动作的一个进行时态。 举例:They pretend to be reading books when the teacher sneakingly stands at the back door.当老师偷偷地站在后门的时候他们假装正在读书(读书与老师站在后门都是过去进行时 态)(JasoOon的回答) Asmanypeople do，youoftenpretend to be doingwork when actuallyyou arejust wasting time online.像很多人一样，你经常假装正在工作，其实是在上网。 群主补充：昨天和今天已提交作业的同学，做得都很好，全部授予小红花。希望你们再接再厉，不要松懈哟。所以下周一出题者为所有已提交作业的同学或者你们选出的代表。

感官动词的用法

1.感官动词用法之一：see, hear, listen to, watch, notice等词，后接宾语，再接动词原形或ing形式。前者表全过程，后者表正在进行。句中有频率词时，以上的词也常跟动词原形。 I heard someone knocking at the door when I fell asleep. (我入睡时有人正敲门) I heard someone knock at the door three times. (听的是全过程) I often watch my classmates play volleyball after school.(此处有频率词often) 若以上词用于被动语态，后面原有动词原形改为带to不定式： We saw him go into the restaurant. →He was seen to go into the restaurant. I hear the boy cry every day. →The boy is heard to cry every day. 2.感官动词用法之二：look, sound, smell, taste, feel可当系动词，后接形容词： He looks angry. It sounds good. The flowers smell beautiful. The sweets taste sweet. The silk feels soft. I felt tired. They all looked tired. 这些动词都不用于被动语态。如：The sweets are tasted sweet.是个病句。注意：如果加介词like,则后不可接形容词，而接名词或代词：

(完整word版)肺功能检查操作流程、目的及注意事项

呼吸内科肺功能检查流程、目的及注意事项 哪些人适应做肺功能检查? 1.慢性阻塞性肺疾病(COPD)、慢性支气管类、肺气肿等呼吸道疾病患者定期复查--监控病程发展； 2.季节性咳喘发作--看是否患有哮喘； 3.有慢性咳嗽、呼吸困难、气促、喘息、胸闷等表现的病人--明确原因； 4.反复上呼吸道感染者--观察肺功能是否有损伤； 5.吸烟并长期咳嗽，或长期大量吸烟者--看小气道功能是否改变； 6.胸片或CT异常--判断肺功能损害程度； 7.麻醉、外科手术前--评估手术风险，以及术后恢复的预测； 8.呼吸疾病临床治疗后的疗效评估和疾病进展评估； 9.健康体检。 哪些人病人不适应做肺功能检查作 绝对禁忌症 1.近3个月患心肌梗死、脑卒中、休克、胸腹部大手术； 2.近4周严重心功能不全、严重心律失常、不稳定性心绞痛； 3.近4周大略血； 4.癫痫发作需要药物治疗； 5.未控制的高血压病 (收缩压>200mHg. 舒张压>100mmHg)； 6.主动脉瘤，严重的甲亢。 相对禁忌症: 1.心率>120次/分； 2.气胸、巨大肺大泡且不准备手术治疗者； 3.孕妇； 4.鼓膜穿孔(需要先堵塞患侧耳道后测定)； 4.近4周呼吸道感染，免疫力低下易感染者； 6.其他:呼吸道传染性疾病(如结核病、流感等)。 受试者准备 1.测试前病人须安静休息15分钟； 2.准确测量身高和体重； 3.体位:可坐可站，坐时要挺胸坐直； 4.检查动作的练习:对受试者吸呼气加以指导。 检查流程： （一）、接通电源，输入信息（编号、姓名、性别、年龄、身高、体重、室内温度、湿度、压强等），接好滤室和口件，指导病人取立姿夹上鼻夹不能漏气、咳嗽，用嘴咬住口件，不能漏气，学会完全用嘴呼吸,并使病人领会测试要点。（二）VC测试: 1.按【VC】键； 2.看到屏幕有示意图时，按【START】键开始呼气； 2.进行平静呼吸2次； 4.缓慢的深呼气至残气位(尽量呼气到不能呼为止）； 5.缓慢的深吸气至肺总量位(尽重吸到不能再吸为止）；

论共同但有区别责任原则

论共同但有区别责任原则 ——全球环境 徐博 （机械与汽车工程系机制2082班） 摘要:文章在结合我国的具体国情的基础上,对我国进行环境污染防治过程中在环境保护法律中适用这一前沿的原则所具有的理论基础以及需要注意的问题进行了探讨。 关键词:京都议定书;共同但有区别责任原则 一、共同但有区别责任原则的主要内容 《京都议定书》第一次设定了具有法律约束力的温气限排额度,是迄今为止国际社会承诺削减温气排放、遏制地球变暖的唯一一项国际公约。结合1994年3月生效的《联合国气候变化框架国际公约》的相关内容可知,共同但有区别责任原则主要内容包含两个方面——共同责任以及有区别责任。由于现实原因的限制或者说是从公平的角度考虑,发达国家和发展中国家在国际环境保护中所要承担的责任的范围、时间、方式、手段等方面是有差异的,从历史和现实的角度出发,对于各国的具体责任的确定,应当兼顾公平与效率,统筹考虑各种因素,在公平和效率之间做出适当的权衡取舍。保护和改善全球环境是全人类的共同利益所在,是世界各国的共同责任。这种共同责任主要体现在:基于“地区生态系统的整体性”,各国,不论其大小、贫富方面的差别都应该采取措施保护和改善其管辖范围内的环境,并防止对管辖范围以外的环境造成损害,同时各国应该在环境方面相互合作和支持等。但是另一方面,由于各国经济发展和工业化的水平不同,废弃物和污染物的排放数量也不同,不应该要求所有的国家承担完全相同的责任。发达国家在自身发展过程中曾经向大气排放大量有害物质,最先并且主要是他们造成了大气的污染,发展中国家不应为他们造成的大气污染后果承担责任。 二、共同但有区别责任原则适用于我国环境法律体系的基础 不可否认,共同但有区别责任原则在全球范围内是适用、且必须加以运用的。一种被证实具有优越性的原则能否在我国的环境法中适用,必须要针对我国的具体国情以及此原则的特征进行分析。 (一)我国在环境保护方面与世界进行了深入的交流和合作,具备运用相应知识的能力 从环境角度来看,世界是一体的,一国环境的污染和破坏都可能引起相关地区甚至全球范围内的环境破坏。我国积极参加全球范围内的环境保护活动,签订相关的环境保护国际协议。我国先后与30多个国家签署了双边环境合作协议或备忘录,与美国、日本、法国、德国、加拿大、俄罗斯等10个国家签订了有关核安全与辐射环境管理的双边合作协议,与联合国环境规划署、联合国开发计划署、国际原子能机构、世界银行、亚洲开发银行、全球环境基金、蒙特利尔议定书多边基金等国际机构建立了密切的合作关系。积极参与了重要国际环境公约的谈判和重要多边环境论坛的活动,参加或签署了气候变化框架公约、生物多样性公约、保护臭氧层的维也纳公约和蒙特利尔议定书、巴塞尔公约、核安全公约等国际环境公约,广泛、深入地开展了有关国际公约的履约工作。表明我国在环境保护方面已经全面与世界接轨,对国际环境保护及其责任履行上的原则有了深入地了解和学习,能够结合我国的具体实际情况合理地移植到我国的相关法律体系中来。

论国际环境法的共同但有区别责任原则

目录 毕业论文诚信承诺书 (2) 摘要 (3) 关键字 (3) 正文 一、共同但有区别责任原则的概述 (3) 二、共同但有区别责任原则的发展 (4) 三、共同但有区别责任原则的性质 (5) 四、共同但有区别责任原则的意义 (6) 五、坚持和发展“共同但有区别责任”原则 (6) 结语 (7) 参考文献 (7)

毕业论文诚信承诺书 本人作为《论国际环境法的共同但有区别责任》一文的作者，郑重承诺： 一、本论文是我在导师的指导下，参考相关文献资料，进行分析研究，独立完成的，其中所引用的文献资料和相关数据，都是真实的，除标明出处的内容外，不包含他人已公开发表的研究成果和学术观点。 二、本论文中若有抄袭他人研究成果和剽窃他人学术观点，本人自愿承担取消毕业论文成绩、交回学历学位证书等一切后果。 学生签名： 年月日注：本承诺书一式二份，一份置于毕业论文分册首页，一份置于过程材料分册末页。

论国际环境法的共同但有区别责任原则 摘要 环境保护已经成为我们时代最为重大的主题之一。世界每一个成员都应当共同承担保护和改善全球环境的责任，环境保护不再是仅限于一个两个国家主权之间的事情。全球性环境问题需要所有国家的共同努力才能得以解决。在对环境问题形成所起的作用上，发达国家和发展中国家扮演者主次不同的角色。如果要让本来就相对贫困的发展中国家在解决目前的全球性问题上承担和发达国家同样的义务，肯定是不公平的，必然会遭到发展中国家的反对。国际环境法的共同但有区别的责任原则“就在这样的背景下产生了，它调解了国家之间的矛盾，促进各国都参与到全球环保事业当中，将不同国情，制度的国家团结成一个“求大同、存小异”合作的整体。共同担有区别的责任原则主要包含两层意思：共同责任和区别责任。它不但是国际法上的一项重要原则，更代表了环境争议思想在适用范围上的扩展，本文主要探讨共同但是有区别的责任的定义、内涵以及环境正义与共同但有区别的责任之间的关系，还有共同但有区别的责任定义的必要性。 关键字 共同但有区别的责任国际发达国家发展中国家 一、共同但有区别责任原则的概述 国际环境法中共同但有区别责任原则因体现谋求优先发展经济的利益诉求,获得大部分发展中国家认同。但该原则的地位、内容一直存有争议。随着中国、印度等发展中大国碳排放日益增长,在后续气候谈判中如仅以发展中国家身份不参加实质减排,将面临极大压力。因此,探讨该原则的地位以及承担责任的依据,对于确定发达国家与发展中国家应对气候变化所应承担的共同责任以及各自应承担的义务,将具有重要意义. 共同但有区别责任主要体现在国际气候大会中表现最为明显，备受关注的联合国第十九次气候变化大会雨2013年11月23日晚在波兰首都华沙落幕，会期比原计划拖延了一整天。经过长达两周的艰难谈判和激烈争吵，特别是会议结束前最后48小时，各国代表挑灯夜战，最终就德班平台决议、气候资金和损失损害补偿机制等焦点议题签署了协议。 但是，由于发达国家不愿承担历史责任，在落实向发展中国家提供资金援助问题上没有诚信，导致政治互信缺失，加上个别发达国家的减排立场严重倒退，致使谈判数次陷入僵局。会议最终经过妥协，达成了各方都不满意、但都能够接受的结果。 《联合国气候变化框架公约》第十九次缔约方会议暨《京都议定书》第九次缔约方会议23日晚打破僵局达成协议后在华沙落下帷幕。尽管大会成果不尽如人意，但中方表示，节能减排是中国可持续发展的内在要求，无论谈判进展如何

感官动词

感官动词的概念和相关考点 1、什么是感官动词？ 听觉：listen to、hear 视觉：look at、seem、watch 嗅觉：smell 触觉：feel、touch 味觉：taste 2、感官动词如何正确使用？ Tom drove his car away. →I saw him drive away. (全过程) 用法一：somebody did sth + I saw this I saw somebody do something. Tom was waiting for the bus. →I saw Tom waiting for the bus. (看不到全过程) 用法二：somebody was doing sth + I saw this I saw somebody doing something 练习： 一、句子翻译 1. I didn,t hear you come in. 2. I suddenly felt sth touch me on the shoulder. 3. I could hear it raining. 4. Listen to the birds singing. 5. Can you smell sth burning? 6. I found Sue in my room reading my letters. 二、灵活运用 1. I saw Ann waiting for the bus. 2. I saw Dave and Helen playing tenins. 3. I saw Clair having her meal. 三、选择最佳选项 1. Did anybody see the accident (happen/happening)? 2. We listen to the old man (tell/telling) his story from beginning to the end. 3. Listen! Can you hear a baby (cry/crying)? 4.—Why did you turn around suddenly? — I heard someone (call/calling) my name. 5. We watched the two men (open/opening) a window and (climb/climbing) through it into house. 6. When we got there, we found our cat (sleep/sleeping) on the table. 四、感官动词的被动语态 Oh，the milk is tasted strange.

pretend的用法总结

pretend的用法总结 以下是小编为大家总结的pretend的用法，希望能帮助大家掌握pretend这个单词，提高英语水平。 pretend to be doing 是强调不定式的动作正在进行的过程中. pretend to do是强调假装要做某事,而不一定正在进行或者是已经发生. 还有一种完成式pretend to have done 强调假装后面的动作已经完成. pretend to be reading就表示他假装正在读书 pretend to sleep 表示他要去睡觉 pretend vt. 假装, 装扮, (作为藉口或理由)伪称 To give a false appearance of; feign: 伪装：显示一副假面貌;伪装： You had to pretend conformity while privately pursuing high and dangerous nonconformism(Anthony Burgess) 当你私下里追求崇高而又危险的新教教义时，你仍得假装信奉国教(安东尼伯吉斯) To claim or allege insincerely or falsely; profess: 假称：不诚实地或虚假地要求或宣称;自称：

doesnt pretend to be an expert. 不要伪称是个专家 To represent fictitiously in play; make believe: 装扮：在戏剧中虚构地扮演;使相信： pretended they were on a cruise. 他们假装在海上巡逻 I cannot pretend to say that you are wrong. 我不敢说你是错误的To take upon oneself; venture: 大胆冒昧地做：使自己承担义务;冒险干某事： v.intr.(不及物动词) To feign an action or a character, as in play. 扮演：假扮某种行为或某个角色，如在戏剧中假扮 To put forward a claim. 自称：提出要求 To make pretensions: 假装，矫作： pretends to gourmet tastes. 自命有美食家的品味 https://www.doczj.com/doc/c41390693.html,rmal (形容词)【非正式用语】 Imitation; make-believe: 模仿的;仿制的： pretend money; pretend pearls.