a r X i v :a s t r o -p h /0312576v 2 11 J a n 2004
S UBMITTED TO A P J –D EC 21,2003
Preprint typeset using L A T E X style emulateapj v.11/26/03
REFLECTIONS OF AGN OUTBURSTS IN THE GASEOUS ATMOSPHERE OF M87
W.F ORMAN 1,P.N ULSEN 1,2,S.H EINZ 3,F.O WEN 4,J.E ILEK 5,A.V IKHLININ 1,6,
M.M ARKEVITCH 1,R.K RAFT 1,E.C HURAZOV 7,6,C.J ONES 1
Submitted to ApJ –Dec 21,2003
ABSTRACT
We combined deep Chandra,ROSAT HRI,and XMM-Newton observations of M87to study the impact of AGN outbursts on its gaseous atmosphere.Many X-ray features appear to be a direct result of repetitive AGN outbursts.In particular,the X-ray cavities around the jet and counter jet are likely due to the expansion of radio plasma,while rings of enhanced emission at 14and 17kpc are probably shock fronts associated with outbursts that began 1?2×107years ago.The effects of these shocks are also seen in brightenings within the prominent X-ray arms.On larger scales,～50kpc from the nucleus,depressions in the surface brightness may be remnants of earlier outbursts.As suggested for the Perseus cluster (Fabian et al.),our analysis of the energetics of the M87outbursts argues that shocks may be the most signi?cant channel for AGN energy input into the cooling ?ow atmospheres of galaxies,groups,and clusters.For M87,the mean power driving the shock outburst,2.4×1043ergs s ?1,is three times greater than the radiative losses from the entire “cooling ?ow”.Thus,even in the absence of other energy inputs,outbursts every 3×107years are suf?cient to quench the ?ow.
Subject headings:galaxies:active -galaxies:individual (M87,NGC4486)-X-rays:galaxies
1.INTRODUCTION
M87(NGC4486)provides a unique laboratory to study the interaction between energy generated by a supermassive black hole and the hot intracluster medium.Its proximity allowed the disk surrounding its active nucleus to be resolved by HST providing a measure for the mass of the central black hole of 3.2×109M ⊙(Harms et al.1993,Ford et al.1994,Macchetto et al.1997).M87’s proximity also provides a unique view of its jet,detected in optical,X-ray,and radio (e.g.,Sparks,Biretta,&Macchetto 1996,Perlman et al.2001,Marshall et al.2002,Harris et al.2003).
M87is the central elliptical in the rich Virgo cluster and is surrounded by an extensive gaseous atmosphere with a mean temperature of ～2?2.5keV (Mathews 1978,Bahcall &Sarazin 1977,Fabricant &Gorenstein 1983,B?hringer et al.2001,Matsushita et al.2002).X-ray structure in the gaseous halo of M87was ?rst reported by Feigelson et al.(1987)using Einstein Observatory https://www.doczj.com/doc/ec7258826.html,ing ROSAT and XMM-Newton observations,B?hringer et al.(1995),Churazov et al.(2001)and Belsole et al.(2001)discussed the relationship between the observed X-ray structure and the radio emission.Like many other optically luminous galaxies at the centers of clusters,M87has been considered to be a classic example of a “cooling ?ow”system,where the gas cooling time is rela-tively short compared to the age of the system (e.g.,Stewart et al.1984,Nulsen &B?hringer 1995,B?hringer et al.2001).However,observations with XMM-Newton have shown that cooling ?ows,like that around M87,deposit cooled gas at much lower rates than expected in the standard cooling ?ow
1
Smithsonian Astrophysical Observatory,Harvard-Smithsonian Center for Astrophysics,60Garden St.,Cambridge,MA 02138;wrf@https://www.doczj.com/doc/ec7258826.html,
2On leave from the University of Wollongong 3MIT,Cambridge,MA
4National Radio Astronomy Observatory,Socorro,NM 878015New Mexico Tech.,Socorro,NM 87801
6Space Research Institute (IKI),Profsoyuznaya 84/32,Moscow 117810,Russia
7MPI für Astrophysik,Karl-Schwarzschild-Strasse 1,85740Garching,Germany
model (Fabian 1994;Peterson et al.2003and references therein).This requires considerable energy input to compen-sate for radiative losses.M87,with its proximity,its active nucleus,jet,and extensive system of radio lobes,provides an ideal system for studying the energy input from the AGN to the hot,cooling gas.
Using radio studies,Owen,Eilek &Kassim (2000;see also Binney 1999)pioneered the view that the mechanical power produced by the supermassive black hole at the center of M87was more than suf?cient to compensate for the en-ergy radiated in X-rays.Tabor &Binney (1993)and Binney &Tabor (1995)developed models without mass deposition and included energy injection from the central AGN.Heinz,Reynolds &Begelman (1998;see also Reynolds,Heinz &Begelman 2001)modelled shock heating of the IGM by an ex-panding radio source.Churazov et al.(2001;see also Kaiser &Binney 2003,Bruggen 2003,De Young 2003,Kaiser 2003)argued that the morphology of the X-ray and radio observa-tions could be explained by radio emitting plasma bubbles buoyantly rising through the hot X-ray emitting gas.These buoyant bubbles could uplift the coolest gas and provide en-ergy input as bubble enthalpy is converted to kinetic energy,then thermalized into the gas in the bubble wake.
The results outlined above relied primarily on pre-Chandra observations of M87that lacked suf?cient angular resolution to allow detailed comparison to the radio structures shown in the Owen et al.(2000)study.Young,Wilson &Mundell (2002)used a 37ksec Chandra observation to con?rm pre-vious structures,as well as to describe several new features including two nearly spherical “edges”at ～45′′and ～3′that they attribute to activity in the nucleus associated with jet production.The Chandra images also show cavities and ?laments in the eastern and southwestern X-ray arms.Young et al.argued that the arms were overpressurized and multi-temperature.Molendi (2002)used XMM-Newton observa-tions to show that the X-ray arms required two-temperature models with gas temperatures in the range kT ～0.8?1keV and kT ～1.6?2.5keV .
In this paper,we combine deep Chandra,ROSAT HRI,and
2Forman et al.
XMM-Newton observations to study the impact of AGN out-bursts on the gaseous atmosphere around M87and the in-teraction of the radio emitting plasma with the hot gas.As others have noted,the Chandra,XMM-Newton,and ROSAT HRI observations show rich structure on many angular scales. These include knots in the jet,surrounding cavities,a coinci-dent X-ray and radio bubble just budding from the southeast of the radio core region,a weak shock,?laments and cav-ities in the east and southwest arms,and an arc-like region of enhanced emission coincident with the outer edge of the southern radio halo.In this paper,we describe the X-ray ob-servations and discuss the origin of these features in M87.
2.OBSERV ATIONAL DETAILS
M87has been well studied at all wavelengths as well as by each new X-ray mission.Here,we describe our analysis for Chandra,XMM-Newton,and the ROSAT HRI.X-ray obser-vations were obtained from the Chandra,XMM-Newton,or HEASARC archives.While Chandra provides unprecedented angular resolution,XMM-Newton and the ROSAT HRI yield large FOV images to study the larger scale structures around M87.We adopt a distance for M87of16Mpc(Tonry et al. 2001)which yields a scale of4.65kpc per arc minute.
For all analyses of radial distributions,projections,and spectra,point sources were detected and then excluded(231 for Chandra)as was the bright M87nucleus and jet.
2.1.Chandra
M87was observed with Chandra on29-30July2000(OB-SID352)and6-8July2002(OBSID2707)for37ksec and 105ksec respectively with ACIS-S at the focus.Details for the July2000and July2002observations are given by Young et al.(2002)and Jordan et al.(2003)respectively.The July 2002observation was used by Jordan et al.(2003)to ana-lyze the point source population of M87.We applied standard screening to the event list,omitting ASCA grades1,5,and7, known hot pixels,bad columns,and chip node boundaries. Because the Virgo cluster is both bright and extended,we used the ACIS S1chip to monitor the instrument background rate in the energy band2.5-6.0keV(see Markevitch2001). We found signi?cant background?aring in both observations and the corresponding time intervals were removed.The remaining exposure times for OBSID’s2707and352were 87.9ksec and30.0ksec for a total observation time of117.9 ksec.For all imaging analyses,we generated images,expo-sure maps,and backgrounds separately and then combined the results in sky coordinates.We normalized the exposure maps between frontside and backside illuminated CCD’s,assuming the emission was characterized by thermal emission from hot gas with kT=2keV.For spectral analyses,we extracted spec-tra separately from each observation and?t the spectra jointly in XSPEC.Response matrices and effective areas were aver-aged by weighting by the observed X-ray emission.
2.2.XMM-Newton
XMM-Newton observed M87for57.4ksec on19June 2000.Details for this observation are given by Bohringer et al.(2001)and Belsole et al.(2001).We report on results ob-tained with the MOS instrument.Calibrated event lists were generated using SAS v5.3.The MOS background was cal-culated using the blank?eld data accumulated over a large number of observations(Lumb et al.2002)For analysis,we used MOS data with patterns in the range0-12and the rec-ommended value of the?ag(XMM_EA).For generating the temperature map,we use one of the MOS response matri-ces provided by the XMM SOC and assume that the same response(corrected for energy dependent vignetting)is appli-cable for all regions.The gas temperature map was calculated as described by Churazov et al.(1996;see also Churazov et al.2003for this method applied to XMM-Newton data for the Perseus cluster).An adaptive smoothing also is applied to the map so that each value of the temperature is calculated using regions containing～https://www.doczj.com/doc/ec7258826.html,parison of the overall structure with the results of direct spectral?tting of individual regions shows good agreement.
2.3.ROSAT HRI
M87was observed seven times with the ROSAT HRI be-tween1992and1997(ROSAT sequence numbers rh700214, rh702081,rh704000,rh701712,rh702774,rh701713, rh702775)for a total observation length of171.6ksec.A de-tailed description of the ROSAT HRI observations is given by Harris,Biretta&Junor(1997)and Harris et al.(2000). We generated images from each observation using PHA chan-nels3-9to reduce the instrumental background and improve the signal-to-noise for the diffuse emission.The images were then summed for further analysis.
3.X-RAY IMAGING
X-ray images of the two merged M87Chandra observations are shown in Fig.1and2.Fig.1a shows the central region at full resolution(1pixel=0.492′′)in the energy band0.5-2.5keV.Fig.1b covers a slightly smaller region and includes 6cm radio contours.Fig.1c labels the features discussed in the text below.Fig.2is an adaptively smoothed image.On the smallest scales,Fig.1and Fig.2show:
?The well-known X-ray jet extending～20′′from the
nucleus with the brightest emission coming from the
nucleus and knot A,and showing emission from at least
seven knots(Marshall et al.2002,Harris et al.2003).
?X-ray cavities surrounding the jet(including one sur-
rounding the location of the unseen counterjet)with an
overall extent described as an ellipse with semi-major
and semi-minor axes respectively of40′′and15′′ori-
ented along the jet direction(approximately west north-
west)and coincident with the bright radio emission
seen at6cm(see Fig.1b).The radio lobe cavities,par-
ticularly the counterjet cavity,are delineated by bright
rims of X-ray emission.
?An X-ray cavity(with a radius of about12′′),delineated
by a bright X-ray rim,coincident with radio emitting
plasma“budding”from the southeast of the6cm radio
lobes.
?An X-ray bright core region,surrounding the6cm ra-
dio lobes,with a radius of approximately50′′with more
pronounced emission to the north(overexposed region
in Fig.3).Young et al.(2002)suggested that an edge
at3.9kpc radius arises from sound waves driven by nu-
clear activity.Alternatively,this structure could origi-
nate either as a cold front(see the XMM-Newton tem-
perature map in Fig.6)or as a sheath of cool material
surrounding the cocoon.The southern edge of the radio
cocoon is bounded by a bright X-ray rim(just south of
the outermost radio contour in Fig.1b).
Re?ections of AGN Outbursts3
?At least four cavities(typical scales of～10′′)extend-
ing into the eastern arm with associated?lamentary
structures that surround them.
To study the emission on larger scales,we have used the Chandra ACIS-S2and S3CCD’s as well as the ROSAT HRI and XMM-NEWTON observations of M87.The Chandra large-scale image was prepared by1)extracting the0.5-2.5 keV images from each pointing,2)generating“exposure”maps(accounting for vignetting,quantum ef?ciency,and bad pixel/columns/gaps with an assumed kT=2keV thermal spectrum to normalize the front and back side CCD chips), 3)smoothing(Gaussian of1′′)each of the images and expo-sure maps,4)dividing each image by its exposure map and5) summing the two?at-?elded images.The resulting Chandra image is shown in Fig.3.
To enhance the view of the faint asymmetric structures,we processed the Chandra,XMM-Newton and ROSAT images to remove the large scale radial surface brightness gradient. Fig.4and Fig.5show the relative deviations of the surface brightness from a radially averaged surface brightness model (β-model for Chandra and ROSAT and an azimuthal average for XMM-Newton)i.e.[Data?Model]/Model.These images show evidence on large scales for buoyant bubbles and ener-getic outbursts powered by the supermassive black hole in the M87nucleus.These features,outside the1′core,are labeled in Fig.4b and Fig.5.The features include:
?a nearly azimuthally symmetric ring of emission with a
leading edge at a radius of14kpc(3′)most prominent
to the north and northwest(see Fig.3and Fig.4),which
we interpret as a weak shock(see below)
?a second partial ring of enhanced emission,just beyond
the14kpc ring,at a radius of17kpc,most prominent
at azimuths of0?60?from west(see Fig.4)that we
also interpret as a shock
?the prominent eastern and southwestern arms that
brighten signi?cantly at approximately the radius of the
14kpc ring
?at radii beyond the14kpc ring,the division of each
arm into two?laments.For the southwestern arm,the
?laments(labeled S1and S2in Fig.4b)turn east while
for the eastern arm,the two?laments(labeled E1and
E2in Fig.4b)turn north.
?a southern arc,at a radius of approximately37kpc
(～8′)seen in Chandra,ROSAT HRI,and XMM-
Newton images(Fig4and Fig5a,b)
?on the largest spatial scales,the ROSAT HRI and
XMM-Newton images in Fig.5a,b show depressions
in surface brightness to the northeast and southwest and
corresponding excesses to the southeast and northwest
(see regions marked“Excess”in Fig.5a,b).
4.XMM-NEWTON TEMPERATURE MAP
The XMM-Newton temperature map with its large?eld of view and high signal to noise(compared to Chandra)is shown in Fig.6and is consistent with the discrete temperature?ts performed by Molendi(2002;see also Belsole et al2001). The continuous nature of our map clearly shows some of the large scale structures.The eastern and southwestern arms are distinctly cooler than the surrounding gas,although we found no abundance differences between the arms and the ambient M87atmosphere.The temperature map shows,at least as clearly as the surface brightness map,the clockwise rotation to the east of the southwestern arm.
Perhaps the most striking feature of the temperature map is the similarity of the eastern and southwestern arms.In partic-ular,the temperatures are similar and at the end of the arms, when they start to deviate from the approximately linear struc-ture,each bends clockwise.
5.ANALYSIS AND INTERPRETATION
We discuss the origin of prominent X-ray features seen in the Chandra,ROSAT HRI,and XMM-NEWTON images in terms of energetic outbursts from the supermassive black hole at the M87nucleus.Previous authors have provided ages for the eastern and southwestern arms and buoyant bubbles(107 years;Churazov et al.2001)and the outer radio lobes(108 years;Owen et al.2000).We note that while we describe the outer radio lobes as buoyant bubbles,they must be con-tinuously resupplied with energetic particles as Owen et al. (2000)have emphasized.
5.1.Gas Density and Temperature Deprojection
To obtain ambient gas density and pressure pro?les(see Fig.7),we deprojected the X-ray surface brightness and gas temperatures in a sector north of the nucleus at azimuths(from north)between?30?and45?,a region chosen for its relative absence of asymmetric structure.The deprojection is standard (Nulsen et al.2002),except for the handling of weights for the outermost region.Because the outer edge of the region is well within the cluster,a model was needed to allow for clus-ter emission beyond the deprojected volume.This was done by assuming that the surrounding gas is isothermal,with a power-law density pro?le(n e∝r?1.09,that accurately matches the pro?le from1′?5′,see Fig.7c).The outermost ring was assumed to represent emission from the surrounding gas and its weight was determined accordingly in the spectral depro-jection.
5.2.X-ray Core and Inner Radio Lobes
The inner radio lobes,the cocoon region,originated in an episode of recent activity.We can use the X-ray observa-tions to estimate the energetics associated with their forma-tion.The counterjet cavity is well-described as an ellipse with semimajor-axes of15′′and19′′on the plane of the sky(see Fig.1c).Using the innermost gas temperature of1.65keV from our deprojection(Fig.7),and assuming the transverse expansion of the cavity is subsonic,we estimate that its age is more than1.7×106years.The one-sidedness and super-luminal motion of the jet suggest that its path is close to our line-of-sight.If the axis of the cavity makes an angle of20?to the line-of-sight(Biretta,Sparks&Macchetto1999),then the head of the cavity is advancing at<5×103km s?1.If the cavity is107years old,the average speed of the head of the cavity is mildly supersonic.
If the cavity is prolate and lies in the plane of the sky,its volume is?2.4×https://www.doczj.com/doc/ec7258826.html,ing the pressure for the in-nermost ring of our deprojection(centered at a radius of22′′), gives pV=1.3×1056erg.If the cavity is relativistic(and the presence of the synchrotron emitting plasma strongly ar-gues in favor of this),then its enthalpy is4pV,otherwise it is 2.5pV.Correcting for the20?angle between the line-of-sight
4Forman et al.
and the axis of the cavity increases the volume of the cavity by a factor～2.9and shifts the center of the cavity to larger radius by the same factor.At this position,the gas pressure is 2.6times smaller,so that our estimate of the enthalpy is only slightly altered,based on the assumption that the pressure in-side the cavity is uniform(due to the high sound speed of the relativistic gas).Note that the fact that the external pressure changes over the extent of the cavity implies that the con?gu-ration must be dynamic–either parts of the lobe far from the nucleus(where the external pressure is lower)are overpres-sured and thus expanding into the gaseous atmosphere,or the inner parts,close to the nucleus,are underpressured,and thus collapsing,or both.The maximum overpressure of a factor of 2.6would imply that the head of the cavity is advancing at a Mach number of1.5.Since the cavity itself is likely oriented close to the line of sight,it is quite possible that the assump-tion of sphericity breaks down in the inner bins and that the derived pressure is therefore an overestimate.In either case, a detailed hydrodynamical model is needed to make a more accurate estimate of the enthalpy,but it is unlikely to increase over our estimate by more than50%,and certainly not by more than a factor of2.6.Doubling the calculated enthalpy to allow for the jet cavity to the west,the total enthalpy of these cavities is?1.1×1057erg.Additional radio emitting plasma and X-ray cavities surround the jet cavities.Therefore,given the bubble formation time calculated below,this material is probably produced in the current outburst as well.Including this material would at most double the total enthalpy of the radio plasma from the outburst.
5.3.Azimuthal Rings
The14kpc(3′)and17kpc(3.75′)Rings
The14kpc ring is the clearest example of a shock-driven feature in M87.Although most prominent to the north and west,it is seen over nearly360?in azimuth centered on the M87nucleus(Fig.4).As described in section5.1,we mea-sured the surface brightness and temperature pro?les in a sec-tor north of the nucleus.The deprojected gas density pro?le is shown in Fig.7,along with the deprojected gas temperature. If we identify the inner radio lobes with the piston that drives this shock,since they are small compared to the volume en-compassed by the expanding front,the event that drove the shock may be treated as instantaneous.If the shock is ex-panding into a spherically symmetric medium,it will become increasingly spherical,regardless of the shape of the initial outburst.Thus we model the outburst required to generate the 14kpc ring by assuming that energy is injected in a single event into the atmosphere by the central AGN.Our estimate of the outburst energy is robust to varying details of the actual outburst.Before the passage of the shock,the gaseous atmo-sphere is hydrostatic and isothermal,with a power law density pro?le n e∝r?1.09,chosen to match the surface brightness pro-?le immediately outside the shock.We derived the parame-ters of the outburst by matching calculated surface brightness pro?les to that observed and verifying that the temperature data were consistent with those calculated.The model that best matches the data is characterized by an energy deposit of 8×1057ergs about107yrs ago and is shown in Fig.7(right panel)compared to the observed surface brightness distribu-tion.The shock is mildly supersonic,with M=v/c s=1.2 (v=950km s?1).A weak temperature enhancement at the position of the ring(Fig.7)is consistent with the calculated model(as is the slight temperature reduction inward of the shock).Although the temperature evidence is not strong,the remarkably spherical appearance of this feature is compelling evidence that it is a weak shock driven by the AGN.This de-scription for the formation of the14kpc ring is similar to that of Ruszkowski et al.(2003)in which impulsive energy in-jection generates weak shocks as the injected energy forms a cocoon in the galaxy atmosphere in the Virgo core.We note that the time estimate,1.1×107years,for the onset of the ac-tivity that gave rise to the14kpc ring is robust and the simple model gives this age to an accuracy of about10%.
A second partial ring is seen to the west at a radius of17kpc
(3.75′)extending over～60?in azimuth(see Fig.4c).To form this surface brightness enhancement,a disturbance trav-eling at the sound speed would have originated approximately 4×106years before the event that created the14kpc ring. The amplitude of the17kpc ring is comparable to that of the 14kpc ring and therefore would require a similar amount of injected energy.The timescale between the two events lies well within the range,105–108yrs,expected for repetitive AGN outbursts.
In our shock model for the14kpc and17kpc rings,one or both may be associated with the in?ation of the inner co-coon.This is consistent with radio source models in which the radio outburst commences with rapid expansion,driving a shock.As the expansion slows,the shock separates from the driver,weakens and becomes more spherical(the“sonic boom phase”in Reynolds,Heinz,&Begelman2001).The current energy input by the jet is estimated to be1044ergs s?1by Bicknell&Begelman(1996).Owen et al.(2000)used the radio observations to derive a minimum value of the instanta-neous energy input by the jet of a few×1044ergs s?1.The energy input is more than suf?cient to power the lobes and generate a roughly spherical pulse.
The spherical shock model provides an estimate of the total energy in the outburst.This energy is signi?cantly greater(a factor of3or more)than the enthalpy of the cavities also cre-ated by the AGN outburst(see section5.2).This suggests that shocks may be the most signi?cant channel of AGN energy input into“cooling?ow”atmospheres in early type galax-ies,groups,and galaxy clusters.Fabian et al.(2003)?nd similar shocks and“edges”around NGC1275in the Perseus cluster.They also argue that the energy deposited as these features dissipate can compensate for the energy radiated by the cooling gas in the inner50kpc core.For M87,the mean power of the shock outburst averaged over the past107 years is2.4×1043erg s?1.Within70kpc,the radiative loss from the“cooling?ow”is～1043ergs s?1(corresponding to 10M⊙yr?1;Stewart et al.1984).Thus,one such outburst every3×107years is suf?cient to quench the cooling?ow in the absence of any other heat source.In addition to the energy input from the outburst we have modelled,energy is also be-ing supplied by the buoyantly rising features seen in the radio maps(Churazov et al.2002).
Southern37kpc(8′)Arc
South of the nucleus at a radius of37kpc(8′),a surface brightness enhancement appears as an arc or partial ring in observations by Chandra,ROSAT HRI,and XMM-Newton (see Fig.4and Fig.5a,b).This partial ring extends over an azimuth of at least45?.Statistically,its signi?cance is shown in the radial pro?le in Fig.8made from the Chandra image. As Fig.5shows,the southern37kpc arc lies just outside the large scale radio lobes characterized by Owen et al.(2000)as the oldest(108yrs)structures in M87.In the model by Chu-
Re?ections of AGN Outbursts5
razov et al.(2001),these radio lobes were originally buoyant bubbles that have risen in the gaseous atmosphere surrounding M87and are now thin disks(“pancakes”)seen in projection. Each108yr old bubble is partially surrounded by gas that has been displaced by the bubble’s rise.This gas could be mate-rial piled up on the edge of the bubble during its expansion or alternatively,gas that was uplifted by the bubble and is drain-ing off the bubble along its sides.The XMM-Newton spectra show that the gas associated with this feature has a similar temperature(kT≈2.5keV)but high abundance(1.2±0.3of solar for an APEC model)compared to other gas at the same radius(0.4-0.5of solar).
Rims of cool gas are a common feature of cavities created by radio lobes(e.g.Finoguenov&Jones2001,McNamara et al.2000,Fabian et al.2002,Blanton et al.2001).In M87we see rims most clearly in the bright edge of the counterjet cav-ity,the southeastern“bud”,and the southern edge of the outer radio lobes.The presence of bright rims over such a wide range of scales illustrates the ability of the radio plasma to ex-clude hot gas and attests to their surprising stability(Nulsen et al.2002).
At the western end of the37kpc arc,a brightness enhance-ment is seen in both the XMM-Newton and ROSAT HRI im-ages(Fig.5a,b).This feature is extended from northwest to southeast(30′′,2.3kpc,in length)and is likely associ-ated with a Virgo cluster member,the E2galaxy NGC4478 (RA=12:30:17.4,DEC=+12:19:43)that is coincident with the X-ray feature.The X-ray luminosity of the galaxy is7×1038 ergs s?1and its optical absolute magnitude is M B=?18.8(for a distance of16Mpc).The X-ray and optical luminosities are consistent with the L x?M B correlation for the emission from hot gas in early type galaxies(e.g.,Forman,Jones& Tucker1985).David,Forman&Jones(1991)showed that early type galaxies with M B=?19would be transitioning from atmospheres with partial to total subsonic winds,assuming a supernova rate of0.15SN Ia per1010L⊙per century(van den Bergh,Maclure&Evans1987).If the supernova rate in NGC4478is slightly less than this assumed value or if some fraction of the supernova energy is not transferred to the hot atmosphere,then NGC4478could maintain a barely sta-ble atmosphere.Such an atmosphere could be ram pressure stripped in the dense Virgo core,producing the extended X-ray emission seen in the ROSAT HRI and XMM-Newton im-ages.Thus,most likely,we are observing the gaseous halo of an elliptical galaxy being stripped by the atmosphere around M87and the feature is probably not associated directly with the southern arc.
Large Scale Surface Brightness Asymmetries
On the largest scales,the XMM-Newton and ROSAT im-ages(Fig.5a,b)show surface brightness enhancements and depressions outside the outer radio lobes and beyond the 37kpc arc.In particular,in30?wide sectors at a radius of50±5kpc,the surface brightness in the ROSAT HRI has a maximum18%above the mean in the northwest and a min-imum10%below the mean in the southwest.At somewhat smaller radii,Fig.5shows higher surface brightness to the southeast,just beyond the outer radio lobe.
Some of these asymmetries could arise from an elliptical gravitational potential or they could result from subtracting an azimuthally symmetric model for the surface brightness from an elliptical distribution.Alternatively,such an asymmetrical distribution could arise from“ghost cavities”(e.g.,Ensslin 1999)of relativistic plasma,produced by earlier epochs of AGN activity,but no longer emitting at observable radio fre-quencies.The outer radio lobes are approximately108years old and,as Owen et al.(2000)argued,their detection requires ongoing energy injection.Any older cavities,at larger radii, may no longer have a connection to the nucleus and,hence, would no longer be detectable at radio wavelengths.
5.4.A Budding Bubble
In most systems,X-ray cavities or radio plasma bubbles generally are consistent with having been directly?lled by an active jet and are aligned with the jet axis or lie on op-posite sides of the active nucleus.Clear examples of such alignments include a wide variety of systems ranging from galaxies with very modest gaseous atmospheres like Cen A (Kraft et al.2003)and M84(Finoguenov&Jones(2001)to rich luminous clusters including Hydra A(McNamara et al. 2000,David et al.2001,Nulsen et al.2002),and Perseus (B?hringer et al.1996,Fabian et al.2002).
While many of the inner X-ray structures in M87are clearly aligned along the direction of the M87jet axis,the southeast-ern bubble(extending from30′′to45′′from the M87nucleus) is an exception(see Fig.1).This bubble corresponds precisely to a radio feature and appears as a“bud”emanating from the southeast of the bright radio core.Fig.1b shows the X-ray image with the6cm radio contours superposed(Hines,Owen &Eilek1989).The surrounding X-ray emission traces the outline of the outer radio contour and shows that the X-ray cavity is?lled with radio emitting plasma.
The“bud”emanates from the inner radio cocoon(just south of the cavity corresponding to the counterjet),almost perpen-dicular to the axis de?ned by the jet.While its origin is likely associated with an outburst from the active nucleus and an episode of energy injection into the inner cocoon,the loca-tion of the bubble may mark a magnetically weak region of the inner cocoon(the counterjet cavity)with buoyancy forces driving the bubble perpendicular to the dominant axis of re-cent activity.
If we assume that the rise of the budding bubble(radius r=11′′,0.85kpc)is governed by buoyancy and limited by the drag of M87’s hot gaseous atmosphere,we can estimate the formation time,τbubble,as the time for the bubble to rise through its own diameter.If R is the distance from the cluster center to the current position of the bubble and M(R)is the total gravitating mass within R,then
τbubble?2R GM(R)?4×106y,(1)
where we have used R=34′′(2.6kpc),the projected distance from the cluster center,and M(R)=1.4×1011M⊙(C?téet al. 2001).C W～0.5is the drag coef?cient for a roughly spher-ical bubble.Since the actual distance to the cluster center almost certainly exceeds the projected distance,this gives a lower limit for the rise time.Furthermore,according to(1), the speed of the bubble,383km s?1,exceeds half of the sound speed and so is overestimated.Thus its rise time is underes-timated,even if the budding bubble lies in the plane of the sky.
During its rapid initial expansion,the boundary of the bub-ble will generally be stable.As a result,the motion of the bubble boundary generally needs to be subsonic before a bub-ble even starts to form.This adds a further delay toτbubble after the outburst,but before the bubble is formed.If we do associate the budding bubble with an energetic nuclear event,
6Forman et al.
then the constraints on its formation timescale make it quite reasonable to associate it with the current outburst(associated with the jet)that commenced about107years ago.
5.5.Buoyant Bubbles and the Structure of the Eastern and
Southwestern Arms
The most striking X-ray features in M87are the two arms that extend east and southwest from the inner lobe region. These also are seen in the90cm image(see Fig.11for a composite X-ray-radio view of M87).Previous spectroscopic studies of the arms have utilized the XMM-Newton observa-tions(Belsole et al.2001,Molendi2002).They?nd that the arms are cool and portions are poorly?t by single tempera-ture components.Our Chandra results agree with these pre-vious analyses,as does the XMM-Newton temperature map (Fig.6).We?nd that the arms require at least two compo-nents(with variable abundances,VMEKAL or V APEC)with the low and high temperature components in the range1-1.5 keV and2-2.7keV respectively.Although the two arms are likely related to the same outburst,we discuss each separately.
Eastern Arm
The eastern X-ray and radio arm begins at the eastern edge of the inner radio cocoon,but its appearance is much more amorphous than that of the southwestern arm(see Fig.1,3, and4).At the base of the?lament(Fig.1and2)are at least four bubbles with sizes comparable to that of the“bud”dis-cussed above and streamers of gas bounding these buoyantly rising bubbles.Typical bubble sizes are～10′′(0.8kpc)in radius and are reminiscent of the“effervescent”heating de-scribed by Begelman(2003).Fig.9shows a projection across one of these“effervescent”bubbles1.25′(5.8kpc)east of the M87nucleus(labeled“bubble”in Fig.1c).
The temperature structure(Fig.6)of the eastern arm shows X-ray features that are consistent with cool material uplifted by a rising torus(Churazov et al.2001).First,the largest concentration of the coolest gas lies midway along the east-ern arm(1′?2′from M87’s nucleus).Second,the cool gas column in the eastern arm narrows at the edge of the radio torus closest to the M87nucleus and then broadens within the torus(labeled“Uplifted Gas”in Fig.4b),just as one might expect for gas uplifted by a buoyant toroidal plasma bubble (see Fig.11and Fig.3and4in Churazov et al.2001).
A projection along the arm,Fig.10,shows a25%brighten-ing at the radial distance of the14kpc ring.A similar bright-ening occurs at about the same angular distance on the south-western arm.While the feature in the southwestern arm is partially obscured by the change from the ACIS S3to S2chip in the Chandra image,it is clearly seen in both the ROSAT HRI and XMM-Newton images(Fig.5).If this brightening is associated with the passage of the same shock that produced the ring,then this arm(and the southwestern arm as well) must lie close to the plane of the sky.
If this brightening does arise from the passage of the shock, it is likely that the so called“radio ear”,the vortex-like struc-ture that forms the end of the bright eastern radio?lament(see Fig.11),falls between the shocks associated with the14kpc and17kpc rings.This could alternatively explain the?at, ring-like appearance of this radio feature,since passage of a shock through a bubble of relativistic plasma embedded in a background of cold thermal material will induce strong vortic-ity in the plasma,turning it into a ring-like structure(Ensslin &Bruggen2002).Combined with the effect of vorticity cre-ation in buoyantly rising bubbles described by Churazov et al.(2001),this could account for the rather?lamentary appear-ance of this feature.
At the end of the eastern arm(～3′east of the M87nu-cleus),the X-ray image(Fig.4)shows an almost circu-lar enhancement(radius of1′centered at RA=12:31:05.397 DEC=+12:25:10.01)extending to the north(beyond the northern“ear”of the radio emitting torus).This circular fea-ture is bounded on three sides by X-ray enhancements(see Fig.4)which originate at the eastern arm and it is bounded to the northwest by a pair of radio arcs(best seen in the90cm image;see Fig.11).The X-ray temperature of this circular region is intermediate in temperature(1.8-1.9keV)as seen in Fig.6and is comparable to that of the end of southeastern arm (as it swings to the east).The two enhancements,labeled E1 and E2in Fig.4c),which bound the circular region,appear similar to the two?laments into which the southwestern arm divides(see below).We suggest that the outer portions of the eastern arm are similar to the southwestern arm,but seen from a different orientation.
Southwestern Arm
The southwestern X-ray arm originates(see Fig.1and Fig.2)as a narrow?lament of width approximately10′′(0.8kpc)at its narrowest when it exits from the bright in-ner core(at a distance of50′′,3.9kpc from the nucleus).The ?lament extends in an almost straight line to the southwest for～2′(9.3kpc).As seen in Fig.11,over this distance it appears uncorrelated with the radio?lament that extends in approximately the same direction.At a distance of about3.4′(15.8kpc),the X-ray?lament bifurcates(the two sections are labeled S1and S2in Fig.4c).and the correspondence be-tween the radio plasma and X-ray gas becomes more direct. The brightest radio emission lies between the two X-ray arms as they both rotate clockwise in the plane of the sky and even-tually turn due east.
Young et al.(2002)suggested that the arms are overpres-surized.Assuming the southwestern arm is a cylinder lying in the plane of the sky,we?nd that the pressure in the arm is roughly twice that of the hotter ambient gas.We found no el-emental abundance differences that could explain the surface brightness enhancement in the arms.However,the pressure difference seems unphysical,since the time for the pressure to come to equilibrium(the sound crossing time of the arm) is short compared to the sound travel time along the length of the narrow arm.Therefore,the axis of the arm would need to make a suf?ciently small angle with our line-of-sight(roughly 15?)to make its projected path length about4times its width, in order to account for its high emission measure.This seems unlikely,given that the brightening along the arm is at a com-parable radius to that of the eastern arm and both are at a ra-dius similar to that of the14kpc(3′)ring.However,in com-puting the overpressure of the arm,we did not include any contribution to the external pressure from non-thermal par-ticles or from magnetic?eld which could contribute to the con?nement.Magnetic tension could also serve to con?ne the gas in the southwestern arm since the radio emission from the southwestern arm appears to spiral around the X-ray gas (see Fig.11).Alternatively,the southwestern arm may not be formed by rising bubbles as seen in the eastern arm,but is instead a thin sheath of gas exterior to a large plasma bub-ble related to the southwestern radio arm.This is consistent with a roughly20%increase in surface brightness from west to east across the arm.
Re?ections of AGN Outbursts7
6.CONCLUSIONS
We have presented a discussion of several of the remarkable structures seen in the Chandra,XMM-Newton,and ROSAT HRI observations of M87.Many of these,particularly the bubbles emanating from the central region,the nearly circu-lar rings of enhanced emission at14kpc and17kpc,and the brightening of the X-ray arms at these radii,can be attributed to AGN outbursts.The14kpc and17kpc rings,similar to the “ripples”seen in the Perseus cluster(Fabian et al.2003),can be interpreted as shock waves driven by the current outburst that began about107years ago.The outburst also in?ated the inner radio lobes(and cocoon).Outbursts like those that pro-duced these shocks can quench the M87cooling?ow,if they occur approximately every3×107years.Since the enthalpy associated with the inner cavities,produced by the outburst, is only30%of the energy of the outburst,shock heating is probably the dominant heating mechanism for the gas in the inner regions of“cooling?ow”systems.
At larger radii,we see highly enriched gas along the outer edge of the southern radio lobe(the37kpc arc).Asymmetric gas distributions at radii of～50kpc may be evidence for older (>108years)outbursts as are the outer radio lobes.
The hot X-ray emitting gas contains re?ections of previ-ous episodes of AGN activity in the form of bubbles and their bright rims,shocks,and buoyantly uplifted gas struc-tures.With the detailed observations at X-ray and radio wave-lengths of M87,we can probe the interaction between the cen-tral AGN,the relativistic plasma,and the X-ray gas.We are beginning to understand the cyclic heating of the X-ray gas and the energy transfer mechanisms between the central su-permassive black hole and the hot gaseous atmosphere that surrounds central cluster galaxies.
We acknowledge stimulating discussions with D.Harris, L.David,M.Begelman,and R.,Sunyaev.This work was supported by NASA contracts NAS8-38248,NAS8-01130, NAS8-03060,the Chandra Science Center,the Smithsonian Institution,and MPI für Astrophysik.
REFERENCES
Bahcall,J.&Sarazin,C.1977,ApJL,213,L99
Belsole,E.et al.2001,A&A,365,L188
Begelman,M.2003,astro-ph/0303040
Bicknell,G.&Begelman,M.1996,ApJ,467,597
Binney,J.&Tabor,G.1995,MNRAS,276,663
Binney,J.1999,in“Proceedings of the Ringberg Castle Workshop,15-19 September1997(eds.Roser&Meisenheimer),Springer(New York),116 Biretta,J,Sparks,W.,Macchetto,F.1999,ApJ,520,621
Blanton,E.L.,Sarazin,C.L.,McNamara,B.R.,&Wise,M.2001,ApJ,558, L15
B?hringer,H.,Nulsen,P.,Braun,R.&Fabian,A.1995,MNRAS,274,L67 B?hringer et al.2001,A&A,365,L181
Bruggen,M.2003,ApJ,592,839
Churazov,E.,Gilfanov,M.,Forman,W.&Jones,C.1996,ApJ,471,673 Churazov,E.,Bruggen,M.,Kaiser,C.,B?hringer,H.&Forman,W.2001, ApJ,554,261
Churazov,E.,Sunyaev,R.,Forman&B?hringer,H.2002,MNRAS,332,729 Churazov,E.,Forman,W.,Jones,C.&B?hringer,H.2003,590,225
C?téet al.2001,ApJ,559,828
David,L.,Forman,W.&Jones,C.1991,ApJ,369,121
David,L.et al.2001,ApJ,557,546
De Young,D.2003,MNRAS,343,719
Ensslin,T.&Bruggen,M.2002,MNRAS,331,1011
Ensslin,T.1999,in Diffuse Thermal and Relativistic Plasma in Galaxy Clusters,p275,astro-ph/9906212
Fabian,A.1994,ARA&A,32,277
Fabian,A.,Celotti,A.,Blundell,K.,Kassim,N.&Perley,R.2002,MNRAS, 331,369
Fabian,A.C.,Sanders,J.S.,Allen,S.W.,Crawford,C.S.,Iwasawa,K., Johnstone,R.M.,Schmidt,R.W.,&Taylor,G.B.2003,MNRAS,344, L43
Fabricant,D.&Gorenstein,P.1983,ApJ,267,535
Feigelson,E.,Wood,P,Schreier,E.,Harris,D.,Reid,M.1987,ApJ,312,101 Finoguenov,A.&Jones,C.2001,ApJL,547,L107
Ford,H.et al.1994,ApJL,435,L27
Forman,W.,Jones,C.&Tucker,W.1985,ApJ,293,102
Harms,R.J.,et al.1994,ApJ,435,L35
Harris,D.,Biretta,J.,&Junor,W.1997,The M87Ringberg Workshop’, September1997,Springer Lecture Notes in Physics Series,eds.Roeser and Meisenheimer(astro-ph/9804200)
Harris,D.E.,Owen,F.N.,Biretta,J.A.,&Junor,W.2000,in Diffuse Thermal and Relativistic Plasma in Galaxy Clusters,ed.H.Bohringer,L.
Feretti,P.Schuecker,&V.K.Kapahi(MPE Rep.271;Garching:MPE), 111(astro-ph/0002464)Harris,D.,Biretta,J.,Junor,W.,Perlman,E.,Sparks,W.&Wilson,A.,2003, ApJL,586,L41
Heinz,S.,Reynolds,c.,Begelman,M.1998,ApJ,501,126
Hines,D.,Owen,F.&Eilek,J.1989,ApJ,347,713
Jordan,A.,C?té,P.,Ferrarese,L.,Blakeslee,J.P.,Mei,S.,Merritt,D., Milosavljevi′c,M.,Peng, E.,Tonry,J.L.,&West,M.J.2003,ApJ, submitted
Kaiser,C.2003MNRAS3431319
Kaiser,C.&Binney,J.2003,MNRAS,338,839
Kraft,R.et al.2003,ApJ,592,129
Lumb,D.,Warwick,R.,Page,M.,&De Luca,A.2002,A&A,389,93 Macchetto,F.,Marconi,A.,Axon,D.J.,Capetti,A.,Sparks,W.,&Crane,P.
1997,ApJ,489,579
McNamara,B.R.,Wise,M.,Nulsen,P.E.J.,David,L.P.,Sarazin,C.L., Bautz,M.,Markevitch,M.,Vikhlinin,A.,Forman,W.R.,Jones,C.,& Harris,D.E.2000,ApJ,534,L135
Markevitch,M.2001,Chandra calibration memo,
https://www.doczj.com/doc/ec7258826.html,/cal/,“ACIS,”“ACIS Background”and
https://www.doczj.com/doc/ec7258826.html,/contrib/maxim/acisbg/COOKBOOK
Marshall,H.,Miller,B.,Davis,D.,Perlman,E.,Wise,M.,Canizares,C., Harris,D.2002,ApJ,564,683
Mathews,W.1978,ApJ,419,213
Matsushita,K.,Belsole,E.,Finoguenov,A.&B?hringer,H.2002,A&A, 386,77
Molendi,S.2002,ApJ,580,815
Nulsen,P.&B?hringer,H.1995,MNRAS,274,1093
Nulsen,P.,David,L.,McNamara,B.,Jones,C.,&Forman,W.2002,ApJ, 568,163
Owen,F.,Eilek,J.&Kassim,N.2000,ApJ,543,611
Perlman,E.S.,Biretta,J.A.,Sparks,W.B.,Macchetto,F.D.,&Leahy,J.P.
2001,ApJ,551,206
Peterson,J.et al.2003,Proceedings of“The Riddle of Cooling Flows in Clusters of Galaxies”eds.Reiprich,Kempner,Soker,astro-ph/0310008 Reynolds,C.,Heinz,S.,Begelman,M.2001,ApJL,549,L179 Ruszkowski,M.,Bruggen,M.&Begelman,M.2003,astro=ph/0310760 Sparks,W.B.,Biretta,J.A.,&Macchetto,F.1996,ApJ,473,254 Stewart,G.,Fabian,A.,Nulsen,P.&Canizares,C.1984,ApJ,278,536 Tabor,G.&Binney,J.1993,MNRAS,263,323
Tonry,J.et al.2001,ApJ,546,681
van den Bergh,S.,McClure,R.&Evans,R.1987,ApJ,323,44
Young,A.,Wilson,A.,Mundell,C.2002,ApJ,579,560
8Forman et al.
F IG.1.—(a)The top left panel shows the central region of M87as seen by the Chandra ACIS-S detector in the energy band0.5to2.5keV with a Gaussian smoothing of1pixel=0.492′′.Several cavities are seen in the counter jet direction as is the beginning of the large scale eastern arm.(b)The top right panel shows the same image at a slightly larger scale with contours(1,5,20,45×10?5JY per0.1×0.1′′pixel)from the6cm radio observations of Hines et al.(1989) superposed on the X-ray image.A“bud”of radio emitting plasma?lls the X-ray cavity to the south-east.The region referred to as the cocoon in the text is the radio emitting plasma?lled region de?ned by the radio contours(excluding the“bud”).X-ray?laments surround the bubbles in the eastern arm.The bottom panel(c)identi?es features discussed in the text.
Re?ections of AGN Outbursts9
F IG.2.—An adaptively smoothed Chandra image(minimum signi?cance4σ)of the central region of M87.Prominent features include the narrow southwestern arm,the bright50′′radius inner core(yellow)which shows an especially sharp jump in surface brightness along the northern edge,and multiple bubbles and surrounding?laments in the core that form the base of the eastern arm.
10Forman et al.
F IG.3.—The merged,?at-?elded Chandra image in the energy band0.5-2.5keV generated by summing the two pointings after?at-?elding and smoothing each separately(see text for details).The prominent eastern and southwestern arms are apparent as is the surface brightness enhancement with an outer edge at 3′radius from the nucleus.
Re?ections of AGN Outbursts11
F IG.4.—The Chandra image(0.5-2.5keV)processed as described in the text to remove the large scale radial surface brightness gradient.Many faint features are seen including1)the bifurcation of the eastern and southwestern arms,2)the brightening at the eastern and southwestern arms,3)the14kpc(3′)ring,4)the 17kpc(3.75′)arc,and5)the faint southern37kpc(8′)arc.The features are labeled in the color image.The circle and arc for the14kpc and17kpc ring and arc are drawn at their outer extents.E1,E2and S1,S2identify the extensions of the eastern and southwestern arms after each has divided.The uplifted gas core (white in the color image)that lies at the end of the eastern arm at the(projected)center of the radio torus is labeled.
12Forman et al.
F IG. 5.—(a-top)The ROSAT HRI and(b-bottom)the XMM-Newton MOS1+MOS2images processed to remove the steep radial surface brightness gradient.Both?gures show asymmetric emission on large scales(beyond the outer radio lobes).The diffuse emission(labeled“Excess”in the ROSAT HRI image)is bright to the east of the southern radio lobe,as well as to the north of the northern lobe.Asymmetric gas distributions at radii of～50kpc may be evidence for older(>108years)outbursts as are the outer radio lobes.The extended emission from NGC4478(labelled in the ROSAT HRI image)and the southern37kpc arc(just outside the outer contour of the southern radio lobe)are seen in both the ROSAT-HRI and XMM-Newton images.
Re?ections of AGN Outbursts13
F IG.6.—The XMM-Newton temperature map generated according to the method described by Churazov et al.(1996)and summarized in the text.The eastern and southwestern arms are cooler than the ambient gas(as already discussed in earlier XMM-Newton analyses e.g.,Belsole et al.2001and Molendi2002).The temperature map is adaptively smoothed to reduce the noise and hence small scale features are necessarily broadened.Contours from the90cm image from Owen et al.are superposed(0.25,2.5,25,250×10?3JY per1.5′′×1.5′′pixel)
.
F IG.7.—(Left)Radial electron density pro?le shows the14kpc(3′)ring.(Center)Deprojected gas temperature.(Right)Model compared to the observed surface brightness pro?le.The deprojected gas density and temperature are derived by?tting the outermost bin and then using the?t results,weighted by the projected emissivity of the outermost ring,as one component of the?t for the next inner ring.Repeating this process inward yields the deprojected temperature and density pro?le.We use the deprojected values of gas density and temperature to calculate gas pressures.
14Forman et al.
F IG.8.—A radial pro?le extracted from the merged Chandra image(0.5-2.5keV)shows the excess emission37kpc from the nucleus of M87.The pro?le was extracted over an azimuth of30?.
Re?ections of AGN Outbursts15
F IG.9.—A projection across one of the“effervescent”bubbles at the base of the eastern arm.This particular bubble is centered1.25′(5.8kpc)east of the M87nucleus(and is labeled“bubble”in Fig.1c).The width of the projection is the bubble diameter,20′′(1.6kpc).
16Forman et al.
F IG.10.—A projection along the eastern arm shows the sharp surface brightness enhancement at a radius of～3′comparable to that of the14kpc ring.A similar brightening is seen at approximately the same distance from the M87nucleus along the southwestern arm(see Fig.4).
Re?ections of AGN Outbursts17
F IG.11.—This?gure combines the X-ray image(red)from Fig.4with the90cm radio map(light blue)of Owen et al.(2000)and emphasizes both the similarities and differences between the X-ray and radio emission.In the eastern arm,the X-ray and radio appear nearly coincident as one might expect for a cool,dense X-ray column generated by buoyant bubbles.The end of the radio arm shows the clear toroidal shape expected from a large buoyant bubble.To the southwest,the radio emission appears to spiral around the narrow X-ray?lament until the X-ray?lament divides and bends to the east.
五年级上册成语解释及近义词反义词和造句大全 囫囵吞枣；【解释】：囫囵：整个儿。把枣整个咽下去，不加咀嚼，不辨味道。比喻对事物不加分析考虑。【近义词】：不求甚解【反义词】融会贯穿[造句];学习不能囫囵吞枣而是要精益求精 不求甚解；bùqiúshènjiě【解释】：甚：专门，极。只求明白个大概，不求完全了解。常指学习或研究不认真、不深入【近义词】：囫囵吞枣【反义词】：精益求精 造句；1；在学习上，我们要理解透彻，不能不求甚解 2；学习科学文化知识要刻苦钻研，深入领会，不能粗枝大叶，不求甚解。 千篇一律；【解释】：一千篇文章都一个样。指文章公式化。也比喻办事按一个格式，专门机械。 【近义词】：千人一面、如出一辙【反义词】：千差万别、形形色色 造句；学生旳作文千篇一律，专门少能有篇与众不同旳，这确实是平常旳练习太少了。 倾盆大雨；qīngpéndàyǔ【解释】：雨大得象盆里旳水直往下倒。形容雨大势急。 【近义词】：大雨如柱、大雨滂沱【反义词】：细雨霏霏牛毛细雨 造句；3月旳天说变就变，瞬间下了一场倾盆大雨。今天下了一场倾盆大雨。 坚决果断；áobùyóuyù：意思；做事果断，专门快拿定了主意，一点都不迟疑，形容态度坚决 近义词；不假思索斩钉截铁反义词；犹豫不决 造句；1看到小朋友落水，司马光坚决果断地搬起石头砸缸。2我坚决果断旳承诺了她旳要求。 饥肠辘辘jīchánglùlù【近义词】：饥不择食【反义词】：丰衣足食 造句；1我放学回家已是饥肠辘辘。2那个饥肠辘辘旳小孩差不多两天没吃饭了 滚瓜烂熟gǔnguālànshóu〔shú)【解释】：象从瓜蔓上掉下来旳瓜那样熟。形容读书或背书流利纯熟。【近义词】：倒背如流【反义词】：半生半熟造句；1、这篇课文我们早已背得滚瓜烂熟了 流光溢彩【liúguāngyìcǎi】解释；光影，满溢旳色彩，形容色彩明媚 造句：国庆节，商场里装饰旳流光溢彩。 津津有味；jīnjīnyǒuwèi解释：兴趣浓厚旳模样。指吃得专门有味道或谈得专门有兴趣。 【近义词】：兴致勃勃有滋有味【反义词】：索然无味、枯燥无味 造句；1今天旳晚餐真丰富，小明吃得津津有味。 天长日久；tiānchángrìjiǔ【解释】：时刻长，生活久。【近义词】：天长地久【反义词】：稍纵即逝 造句：小缺点假如不立即改掉, 天长日久就会变成坏适应 如醉如痴rúzuìrúchī【解释】：形容神态失常，失去自制。【近义词】：如梦如醉【反义词】：恍然大悟造句；这么美妙旳音乐，我听得如醉如痴。 浮想联翩【fúxiǎngliánpiān解释】：浮想：飘浮不定旳想象；联翩：鸟飞旳模样，比喻连续不断。指许许多多旳想象不断涌现出来。【近义词】：思绪万千 造句；1他旳话让人浮想联翩。2:这幅画饱含诗情，使人浮想联翩，神游画外，得到美旳享受。 悲欢离合bēihuānlíhé解释；欢乐、离散、聚会。泛指生活中经历旳各种境遇和由此产生旳各种心情【近义词】：酸甜苦辣、喜怒哀乐【反义词】：平淡无奇 造句；1人一辈子即是悲欢离合,总要笑口常开,我们旳生活才阳光明媚. 牵肠挂肚qiānchángguàdù【解释】：牵：拉。形容十分惦念，放心不下 造句；儿行千里母担忧，母亲总是那个为你牵肠挂肚旳人 如饥似渴rújīsìkě：形容要求专门迫切，仿佛饿了急着要吃饭，渴了急着要喝水一样。 造句；我如饥似渴地一口气读完这篇文章。他对知识旳如饥似渴旳态度造就了他今天旳成功。 不言而喻bùyánéryù【解释】：喻：了解，明白。不用说话就能明白。形容道理专门明显。 【近义词】：显而易见【反义词】：扑朔迷离造句；1珍惜时刻，好好学习，那个道理是不言而喻旳 与众不同；yǔzhòngbùtóng【解释】：跟大伙不一样。 〖近义词〗别出心裁〖反义词〗平淡无奇。造句； 1从他与众不同旳解题思路中，看出他专门聪慧。2他是个与众不同旳小孩
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 导读：悲惨的近义词 悲凉(注释:悲哀凄凉：～激越的琴声。) 悲惨的反义词 幸福(注释:个人由于理想的实现或接近而引起的一种内心满足。追求幸福是人们的普遍愿望，但剥削阶级把个人幸福看得高于一切，并把个人幸福建立在被剥削阶级的痛苦之上。无产阶级则把争取广大人民的幸福和实现全人类的解放看作最大的幸福。认为幸福不仅包括物质生活，也包括精神生活;个人幸福依赖集体幸福，集体幸福高于个人幸福;幸福不仅在于享受，而主要在于劳动和创造。) 悲惨造句 1.一个人要发现卓有成效的真理，需要千百个人在失败的探索和悲惨的错误中毁掉自己的生命。 2.贝多芬的童年尽管如是悲惨，他对这个时代和消磨这时代的地方，永远保持着一种温柔而凄凉的回忆。 3.卖火柴的小女孩在大年夜里冻死了，那情景十分悲惨。 4.他相信，他们每个人背后都有一个悲惨的故事。 5.在那次悲惨的经历之后，我深信自己绝对不是那种可以离家很远的人。 6.在人生的海洋上，最痛快的事是独断独航，但最悲惨的却是回头无岸。 7.人生是艰苦的。对不甘于平庸凡俗的人那是一场无日无夜的斗
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） 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语： 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势，忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中
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...
“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 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
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
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） 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 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 【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 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。
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 【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?。
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