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Detection of HI 21cm Absorption by the Warm Neutral Medium C.L.Carilli National Radio Astronomy Observatory,P.O.Box O,Socorro,NM,87801K.S.Dwarakanath Raman Research Institute,Bangalore 560080,India W.M.Goss National Radio Astronomy Observatory,P.O.Box O,Socorro,NM,87801Received To appear in the Astrophysical Journal (letters)
ABSTRACT
We have detected HI21cm line absorption by the Warm Neutral Medium (WNM)using the Westerbork Synthesis Radio Telescope.The absorption was detected toward Cygnus A at LSR velocities of–40and–70km s?1.These two velocity ranges were previously identi?ed as being relatively free of cold absorbing clouds.The measured optical depth for the WNM along the line of sight to Cygnus A is8.9±1.9×10?4at–70km s?1,and8.5±2.0×10?4at–40 km s?1,with corresponding spin temperatures of6000±1700K and4800±1600 K,respectively.The volume?lling factor for the WNM appears to be fairly high (f≈0.4).
Subject headings:ISM:structure and atoms–Galaxy:fundamental parameters–Radio Lines:ISM
1.Introduction
Early observations of the21cm line of neutral hydrogen in emission and absorption in the Galaxy showed that toward any given direction the HI line seen in emission was always broader than the corresponding HI absorption line.In addition,most lines of sight showed a broad HI emission line with no corresponding HI absorption(Clark,Radhakrishnan,
&Wilson1962,Clark1965,Radhakrishnan et al.1972).These observations led to the proposal of a‘raisin-pudding’model of the interstellar medium(Field,Goldsmith,&Habing 1969),in which dense cool HI clouds at102K(the Cold Neutral Medium;CNM)are enveloped by a warmer,lower density gas at104K(the Warm Neutral Medium;WNM). More recent models for the interstellar medium include a high?lling factor,Hot Ionized Medium(HIM)at106K,resulting from supernovae explosions(McKee and Ostriker1977). The phases of the interstellar medium are thought to be in pressure equilibrium,although the relative?lling factors of the di?erent phases remain uncertain,and the?lling factors may vary with position in galaxies(Brinks1990,Braun and Walterbos1992).
Kulkarni and Heiles(1988)point out that of all the phases of the interstellar medium (ISM),the WNM remains the least well understood.Although HI21cm emission from the WNM is detected easily in every direction in the sky,an accurate value for the temperature of the WNM is lacking.The standard method with which to determine the temperature of interstellar HI is to compare HI column densities determined by observation of the21cm line in emission in a given region,with those determined by observation of21cm absorption towards background continuum sources(Clark1965).The result is the excitation,or spin temperature,of the gas.The spin temperature,T s,is thought to be close to the kinetic temperature in most Galactic environments.There are three well known problems with this method.The?rst is that one has to interpolate HI column densities determined o?-source to the position of the continuum source.For the WNM this is not a severe problem,since
the column density distribution appears to be fairly smooth on scales≥10′(Kalberla, Schwarz,and Goss1985).Second,when looking for absorption by the WNM,there is the confusion caused by the plethora of absorption lines arising in the CNM.And third,there is the problem of having both emission and absorption in the on-source beam,and the related problem of‘stray-radiation’,or emission coming in through the sidelobes of the telescope beam.This is especially a problem for single dish observations,for which beam sizes are typically much larger than the background continuum sources.
Kulkarni and Heiles(1988)review measurements of the temperature of the WNM. They conclude that the current data,which entails mostly lower limits to T s,are consistent with a temperature range of5000K to8000K for most of the WNM.They emphasize that the current data are sparse,and that‘observational con?rmation of this conclusion is crucial.’The single existing experiment claiming detection of absorption by the WNM is that by Mebold and Hills(1975).They studied HI emission and absorption in the vicinity of the bright extragalactic radio source Cygnus A using the E?elsberg100m telescope. Their experiment consisted of eight o?-source pointings encircling the continuum source,to determine the HI column density distribution in the region,and on-source observations to look for absorption.They found two inter-arm velocity ranges with no narrow absorption features due to the CNM.At these velocities their on-source spectrum of Cygnus A shows HI in emission,however,the amount of emission seen on-source is less than that expected from the interpolation of the o?-source pointings to the source position.From this they infer absorption towards the continuum source.Mebold and Hills estimate an optical depth for the WNM between6×10?4and11×10?4,and a spin temperature between6400K and 7800K.Kalberla,Mebold,and Reich(1980)re-analyzed these data,correcting for stray radiation,and reduced the spin temperature estimates by about20%.
In this letter we present a direct veri?cation of absorption toward Cygnus A in the
CNM-free velocity ranges using the Westerbork Synthesis Radio Telescope(WSRT).We then derive the spin temperature for the WNM in the two CNM-free velocity ranges using the WSRT absorption measurements and emission spectra from the E?elsberg and Dwingeloo telescopes.We discuss these results in terms of standard equilibrium models for the two-phase neutral atomic ISM.
2.Observations of CNM-free Regions toward Cygnus A
The CNM-free LSR velocity ranges toward Cygnus A are from–40to–36km s?1,and –63to–78km s?1,corresponding to inter-arm velocities,between the Orion(0km s?1), Perseus(–50km s?1),and Outer(-85km s?1)spiral arms(Mebold and Hills1975).We have searched for absorption by the WNM at these inter-arm velocities using the WSRT. Using an interferometer mitigates problems of confusion by stray radiation and in-beam emission.Observations were made on May24and25,1996,July15and16,1996,June28 and29,1997,and August22and23,1997,for12hours each day.The total bandwidth was 1.25MHz with255spectral channels after Hanning smoothing,corresponding to1km s?1 velocity resolution,centered at an LSR velocity of–45km s?1.Absolute?ux calibration and initial phase calibration were performed using3C286,and residual phase errors were corrected through self-calibration using a continuum data set made from line-free channels.
An accurate bandpass was determined using frequency switching to‘high’and‘low’frequencies by±1.25MHz on Cygnus A itself.The cycle time for bandpass calibration was two hours,with a50%duty cycle,and the bandpass for each cycle was the average of the high and low frequency settings.An estimate of the accuracy of the bandpass calibration process was obtained by applying the‘high’frequency bandpass solutions to the‘low’frequency spectra.The residual fractional deviations were generally≤1.7×10?4.We adopt this value as a conservative estimate of optical depth errors introduced by the bandpass
calibration process.
The visibility data from each day’s observation were reduced independently using the Astronomical Image Processing System(AIPS).The continuum emission was subtracted using the AIPS task UVLIN,which performs a linear?t to the line-free channels for each visibility,and the data from the eight days were then combined.Spectral line image‘cubes’were constructed from the combined data,and the point response function of the array deconvolved,using the AIPS task IMAGR.The Gaussian restoring CLEAN beam had a FWHM=30′′×15′′with a major axis oriented north-south.
The continuum image of Cygnus A made from line-free channels is shown in Figure1. The observed total?ux density at1.4GHz for Cygnus A was within2%of the expected value of1575Jy(Baars et al.1977).The source is characterized by two‘hot spots’of emission at the source extremities,separated by2′,with a low frequency‘bridge’of emission connecting the two hot spots.In the following section we analyze spectra taken at the the Northwest(NW)and Southeast(SE)hot spots.The peak surface brightness is346Jy beam?1for the NW hot spot and398Jy beam?1for the SE hot spot.
The HI absorption spectra toward the SE and NW peaks of Cygnus A are shown in Figure2.The spectra show deep,narrow lines due to the CNM,clustered around the spiral arm velocities(0,–50,and–85km s?1),with optical depths approaching0.5.There are signi?cant variations in optical depth for these narrow lines between the two lines of sight separated by2′.Small scale structure in the CNM is a well studied phenomenon(Dieter et al.1976,Diamond et al.1989,Deshpande et al.1992,Frail et al.1994,Davis,Diamond, and Goss1996),and a detailed analysis of the CNM structure toward Cygnus A will be presented elsewhere.The root mean square(rms)noise per channel in these spectra is0.1 mJy channel?1,corresponding to an rms optical depth(σ)of about2.5×10?4per channel.
Note the lack of deep,narrow absorption features in the inter-arm velocity ranges from
–40to–36km s?1(region‘B’in the spectra),and–63to–78km s?1(region‘A’),as?rst pointed out by Mebold and Hills(1975).Figures3&4show these same spectra with an expanded?ux and optical depth scale in order to investigate possible absorption in these two CNM-free velocity ranges.The observed(continuum subtracted)surface brightnesses in regions A and B appear to be signi?cantly below zero in all the spectra.The mean optical depth values in regions A and B are listed in Table1.The errors are a(quadratic)sum of the sensitivity error(ie.the rms in o?-line channels after averaging over the speci?ed number of channels),and the estimated error due to bandpass calibration.
The optical depth in velocity region B is marginally higher toward the SE source relative to the NW source(1.8σ).However the SE source spectrum shows a narrow absorption line by the CNM at–30km s?1which is not seen toward the NW source.The wing of this line might perturb the measured value in region B.Similarly,the spectrum of the SE component in velocity region A shows what might be a narrow,weak absorption component at–69km s?1.In the analysis below we use the optical depths in regions A and B averaged over both SE and NW spectra(row three in Table1),with errors as dictated by each measurement.
We are con?dent that the?nite optical depths observed at the CNM-free velocities are reliable for a number of reasons.First,the observed optical depths are signi?cantly higher than the estimated accuracy of the bandpass calibration.Second,we have analyzed spectra from data taken from the four epochs separately(May and July1996,and June and August 1997),and obtain consistent results for each epoch.And third,we have?t Gaussian models to the strong absorption lines nearest in velocity to the CNM-free regions,and we?nd that the?nite optical depths seen in these regions are not due to the wings of the strong lines. We should emphasize that we cannot rule-out a model in which the?nite optical depth seen at the CNM-free velocities toward Cygnus A are due to a‘continuum’of low optical depth
cold clouds.If this were the case,the optical depths quoted in Table1would be strictly upper limits to the true optical depth of the WNM,and the spin temperature values quoted below then become lower limits.
3.Discussion
We can combine our measurement of the HI21cm optical depth of the WNM with the emission measurements of Mebold and Hills(1975)to obtain a lower limit to the spin temperature of the WNM,using the low-optical depth approximation:T B=τT s,whereτis the optical depth to21cm absorption,and T B is the brightness temperature of the21cm emission in the absence of absorption.
One measurement of the emission spectrum in the direction of Cygnus A is the
E?elsberg100m spectrum of Mebold and Hills(1975),which entailed the average of eight emission pro?les taken at distances of20′from Cygnus A in a symmetric star pattern centered on Cygnus A.The brightness temperatures in velocity ranges A and B are given in row four of Table1.These are the values of Mebold and Hills reduced by20%to correct for stray radiation(Kalberla et al.1980).Mebold and Hills quote an error of1K for these measurements.A second measurement is from the all-sky HI survey of Hartmann and Burton(1997),using the Dwingeloo25m telescope,and corrected for stray radiation. The Dwingeloo values are given in row?ve of Table1,where we have averaged four measurements surrounding Cygnus A at distances of about20′.The errors represent the scatter in the measurements.Although the resolutions of the two observations are di?erent (11′for E?elsberg and30′for Dwingeloo),the T B values agree to within the errors.For the calculation of spin temperatures we use the(error weighted)mean T B values listed in row six of Table1.The resulting spin temperature values for velocity regions A and B are listed in row seven of Table1,where the errors are a quadrature sum of errors on the brightness
temperature measurement and the optical depth measurement.
The Galactic coordinates for Cygnus A are l=76o,b=5.8o.The implied distances to the gas in velocity ranges A and B are about12kpc and9kpc,respectively,as derived from the Galactic rotation curve of Burton(1988).The height of this gas from the plane, z,is then:z≈1kpc.A very rough estimate of the pathlength through the gas can be derived by assuming that the velocity ranges are set by Galactic rotation,leading to0.9kpc and0.4kpc for A and B,respectively.Then using the HI column densities calculated from Table1leads to a mean density for the WNM in velocity ranges A and B toward Cygnus A of:
almost any HI cloud observable in the21cm line.’The current limit to the di?use Galactic Lyαphoton density in the solar neighborhood is:n Lyα<2.5×10?6cm?3(Holberg1986). This limit is su?cient to maintain T s≈T k in the WNM if T k～3000K(Field1958).If the value of n Lyαis considerably below10?6cm?3in the WNM,then T s could fall signi?cantly below T k.For example,Corbelli and Salpeter(1993)?nd that temperature equilibrium between T s and T k may not hold in the outer disks of spiral galaxies,where N(HI)≤few ×1019,if the only source of ionizing radiation is the extragalactic background.Until a direct measurement of n Lyαin the WNM becomes available,we can only assume that T s≈T k in the disk of the Galaxy.
The most detailed analysis of the equilibrium state of neutral hydrogen in the interstellar medium is the work of Wol?re et al.(1995).The primary heating mechanism is photoelectric emission from dust grains,while cooling is dominated by?ne structure lines from heavy elements(predominantly Carbon),and by hydrogen recombination lines in warmer regions.In their standard model for neutral hydrogen in the Galactic plane they show that two stable phases exist:(i)the CNM with T k between40K and200K, and(ii)the WNM with T k between5500K and8700K,for ISM pressures in the range of1to5×10?13dyne cm?2.It is interesting that the measured values of T s in the lower pressure(https://www.doczj.com/doc/fe16313263.html,rger z)WNM toward Cygnus A(Table1)are generally consistent with these ranges for the neutral,two-phase ISM model of Wol?re et al.(1995).Corbelli and Salpeter(1993)point out that equality between T s and T k could be used to argue that the ionizing radiation?eld for the WNM is well above the extragalactic background,and hence that‘relevant energy inputs from local sources become necessary.’While the current data toward Cygnus A are consistent with the value of T s being close to the model value of T k for the WNM,more accurate values for T s and T B for the neutral hydrogen,and n Lyα,are needed to provide a fully constrained physical model for the Galactic WNM.
The National Radio Astronomy Observatory(NRAO)is a facility of the National Science Foundation,operated under cooperative agreement by Associated Universities,Inc.. The Westerbork Synthesis Radio Telescope is operated by the Netherlands Foundation for Research in Astronomy with?nancial support from the Netherlands Organization for Scienti?c Research(NWO).We wish to thank K.Anantharamiah,W.B.Burton,A.A. Deshpande,G.Field,D.Hartmann,C.Heiles,S.Kulkarni,U.Mebold,G.Srinivasan,and the referee for useful comments on this work.
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Table1.
A B
-67to-76km s?1-36to-40km s?1
Figure Captions
Figure1–A continuum image of Cygnus A at1.4GHz made using line-free channels from the WSRT observations.The total?ux density is1575Jy.The contours are a geometric progression in the square root of two.The?rst level is5Jy/beam.Dotted contours are negative levels.The FWHM of the Gaussian restoring beam is30′′×15′′with the major axis oriented north-south.
Figure2–The upper frame shows the HI absorption spectrum toward north-west peak of Cygnus A.The spectral resolution in this,and subsequent,spectra is1km s?1channel?1. The spectrum has been converted to optical depth using the continuum surface brightness of346Jy/beam at the resolution of Figure1.The velocity scale is LSR.The CNM-free velocity ranges are labeled‘A’and‘B’.The lower frame shows the corresponding spectrum of the south-east peak,where the continuum surface brightness is398Jy/beam.
Figure3–The upper frame shows the HI absorption spectrum toward the north-west peak of Cygnus A,after subtracting the continuum surface brightness of346Jy/beam.The velocity scale is LSR.The lower frame shows the same spectrum converted to optical depth using the continuum surface brightness of346Jy/beam.The optical depth scale has been expanded to show low optical depth absorption.The CNM-free velocity ranges A and B are indicated.
Figure4–The upper frame shows the HI absorption spectrum toward the south-east peak of Cygnus A,after subtracting the continuum surface brightness of398Jy/beam.The velocity scale is LSR.The lower frame shows the same spectrum converted to optical depth using the continuum surface brightness of398Jy/beam.The optical depth scale has been expanded to show low optical depth absorption.The CNM-free velocity ranges A and B are indicated.
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●I wonder if it’s because I have been at school for so long that I’ve grown so crazy about going home. ●It is because she wasn’t well that she fell far behind her classmates this semester. ●I can well remember that there was a time when I took it for granted that friends should do everything for me. ●In order to make a difference to society, they spent almost all of their spare time in raising money for the charity. ●It’s no pleasure eating at school any longer because the food is not so tasty as that at home. ●He happened to be hit by a new idea when he was walking along the riverbank. ●I wonder if I can cope with stressful situations in life independently. ●It is because I take things for granted that I make so many mistakes. ●The treasure is so rare that a growing number of people are looking for it. ●He picks on the weak mn in order that we may pay attention to him. ●It’s no pleasure being disturbed whena I settle down to my work. ●I can well remember that when I was a child, I always made mistakes on purpose for fun. ●It’s no pleasure accompany her hanging out on the street on such a rainy day. ●I can well remember that there was a time when I threw my whole self into study in order to live up to my parents’ expectation and enter my dream university. ●I can well remember that she stuck with me all the time and helped me regain my confidence during my tough time five years ago. ●It is because he makes it a priority to study that he always gets good grades. ●I wonder if we should abandon this idea because there is no point in doing so. ●I wonder if it was because I ate ice-cream that I had an upset student this morning. ●It is because she refused to die that she became incredibly successful. ●She is so considerate that many of us turn to her for comfort. ●I can well remember that once I underestimated the power of words and hurt my friend. ●He works extremely hard in order to live up to his expectations. ●I happened to see a butterfly settle on the beautiful flower. ●It’s no pleasure making fun of others. ●It was the first time in the new semester that I had burned the midnight oil to study. ●It’s no pleasure taking everything into account when you long to have the relaxing life. ●I wonder if it was because he abandoned himself to despair that he was killed in a car accident when he was driving. ●Jack is always picking on younger children in order to show off his power. ●It is because he always burns the midnight oil that he oversleeps sometimes. ●I happened to find some pictures to do with my grandfather when I was going through the drawer. ●It was because I didn’t dare look at the failure face to face that I failed again. ●I tell my friend that failure is not scary in order that she can rebound from failure. ●I throw my whole self to study in order to pass the final exam. ●It was the first time that I had made a speech in public and enjoyed the thunder of applause. ●Alice happened to be on the street when a UFO landed right in front of her. ●It was the first time that I had kept myself open and talked sincerely with my parents. ●It was a beautiful sunny day. The weather was so comfortable that I settled myself into the
高中英语~词性~句子成分~语法构成 第一章节：英语句子中的词性 1.名词：n. 名词是指事物的名称，在句子中主要作主语.宾语.表语.同位语。 2.形容词;adj. 形容词是指对名词进行修饰~限定~描述~的成份，主要作定语.表语.。形容词在汉语中是（的）.其标志是: ous. Al .ful .ive。. 3.动词：vt. 动词是指主语发出的一个动作，一般用来作谓语。 4.副词：adv. 副词是指表示动作发生的地点. 时间. 条件. 方式. 原因. 目的. 结果.伴随让步. 一般用来修饰动词. 形容词。副词在汉语中是（地）.其标志是：ly。 5.代词：pron. 代词是指用来代替名词的词，名词所能担任的作用，代词也同样.代词主要用来作主语. 宾语. 表语. 同位语。 6.介词：prep.介词是指表示动词和名次关系的词，例如：in on at of about with for to。其特征：
介词后的动词要用—ing形式。介词加代词时，代词要用宾格。例如：give up her（him）这种形式是正确的，而give up she（he）这种形式是错误的。 7.冠词：冠词是指修饰名词，表名词泛指或特指。冠词有a an the 。 8.叹词：叹词表示一种语气。例如：OH. Ya 等 9.连词：连词是指连接两个并列的成分，这两个并列的成分可以是两个词也可以是两个句子。例如：and but or so 。 10.数词：数词是指表示数量关系词，一般分为基数词和序数词 第二章节：英语句子成分 主语：动作的发出者，一般放在动词前或句首。由名词. 代词. 数词. 不定时. 动名词. 或从句充当。 谓语：指主语发出来的动作，只能由动词充当，一般紧跟在主语后面。 宾语：指动作的承受着，一般由代词. 名词. 数词. 不定时. 动名词. 或从句充当. 介词后面的成分也叫介词宾语。 定语：只对名词起限定修饰的成分，一般由形容
M A: Has the case been closed yet? B: No, the magistrate still needs to decide the outcome. magistrate n.地方行政官，地方法官，治安官 A: I am unable to read the small print in the book. B: It seems you need to magnify it. magnify vt.１．放大，扩大；２．夸大，夸张 A: That was a terrible storm. B: Indeed, but it is too early to determine the magnitude of the damage. magnitude n.１．重要性，重大；２．巨大，广大 A: A young fair maiden like you shouldn’t be single. B: That is because I am a young fair independent maiden. maiden n.少女，年轻姑娘，未婚女子 a.首次的，初次的 A: You look majestic sitting on that high chair. B: Yes, I am pretending to be the king! majestic a.雄伟的，壮丽的，庄严的，高贵的 A: Please cook me dinner now. B: Yes, your majesty, I’m at your service. majesty n.１．［Ｍ－］陛下（对帝王，王后的尊称）；２．雄伟，壮丽，庄严 A: Doctor, I traveled to Africa and I think I caught malaria. B: Did you take any medicine as a precaution? malaria n.疟疾 A: I hate you! B: Why are you so full of malice? malice n.恶意，怨恨 A: I’m afraid that the test results have come back and your lump is malignant. B: That means it’s serious, doesn’t it, doctor? malignant a.１．恶性的，致命的；２．恶意的，恶毒的 A: I’m going shopping in the mall this afternoon, want to join me? B: No, thanks, I have plans already. mall n.（由许多商店组成的）购物中心 A: That child looks very unhealthy. B: Yes, he does not have enough to eat. He is suffering from malnutrition.
意见应以事实为根据. 3 来自辞典例句 192. The bombers swooped ( down ) onthe air base. 轰炸机 突袭 空军基地. 来自辞典例句 193. He mounted their engines on a rubber base. 他把他们的发动机装在一个橡胶垫座上. 14 来自辞典例句 194. The column stands on a narrow base. 柱子竖立在狭窄的地基上. 14 来自辞典例句 195. When one stretched it, it looked like grey flakes on the carvas base. 你要是把它摊直, 看上去就象好一些灰色的粉片落在帆布底子上. 18 来自辞典例句 196. Economic growth and human well - being depend on the natural resource base that supports all living systems. 经济增长和人类的福利依赖于支持所有生命系统的自然资源. 12 1 来自辞典例句 197. The base was just a smudge onthe untouched hundred - mile coast of Manila Bay. 那基地只是马尼拉湾一百英里长安然无恙的海岸线上一个硝烟滚滚的污点. 6 来自辞典例句 198. You can't base an operation on the presumption that miracles are going to happen. 你不能把行动计划建筑在可能出现奇迹的假想基础上.
英语造句大全English sentence 在句子中，更好的记忆单词！ 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character. （2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n.
主语+谓语 1. 理解主谓结构 1) The students arrived. The students arrived at the park. 2) They are listening. They are listening to the music. 3) The disaster happened. 2．体会状语的位置 1) Tom always works hard. 2) Sometimes I go to the park at weekends.. 3) The girl cries very often. 4) We seldom come here. The disaster happened to the poor family. 3. 多个状语的排列次序 1) He works. 2) He works hard. 3) He always works hard. 4) He always works hard in the company. 5) He always works hard in the company recently. 6) He always works hard in the company recently because he wants to get promoted. 4. 写作常用不及物动词 1. ache My head aches. I’m aching all over. 2. agree agree with sb. about sth. agree to do sth. 3. apologize to sb. for sth. 4. appear (at the meeting, on the screen) 5. arrive at / in 6. belong to 7. chat with sb. about sth. 8. come (to …) 9. cry 10. dance 11. depend on /upon 12. die 13. fall 14. go to … 15. graduate from 16. … happen 17. laugh 18. listen to... 19. live 20. rise 21. sit 22. smile 23. swim 24. stay (at home / in a hotel) 25. work 26. wait for 汉译英： 1.昨天我去了电影院。 2.我能用英语跟外国人自由交谈。 3.晚上7点我们到达了机场。 4.暑假就要到了。 5.现在很多老人独自居住。 6.老师同意了。 7.刚才发生了一场车祸。 8.课上我们应该认真听讲。9. 我们的态度很重要。 10. 能否成功取决于你的态度。 11. 能取得多大进步取决于你付出多少努力。 12. 这个木桶能盛多少水取决于最短的一块板子的长度。
【it's time to和it's time for】 ——————这其实是一个句型,只不过后面要跟不同的东西. ——————It's time to跟的是不定式（to do）.也就是说,要跟一个动词,意思是“到做某事的时候了”.如： It's time to go home. It's time to tell him the truth. ——————It's time for 跟的是名词.也就是说,不能跟动词.如： It's time for lunch.(没必要说It's time to have lunch) It's time for class.(没必要说It's time to begin the class.) They can't wait to see you Please ask liming to study tonight. Please ask liming not to play computer games tonight. Don’t make/let me to smoke I can hear/see you dance at the stage You had better go to bed early. You had better not watch tv It’s better to go to bed early It’s best to run in the morning I am enjoy running with music. With 表伴随听音乐 I already finish studying You should keep working. You should keep on studying English Keep calm and carry on 保持冷静继续前行二战开始前英国皇家政府制造的海报名字 I have to go on studying I feel like I am flying I have to stop playing computer games and stop to go home now I forget/remember to finish my homework. I forget/remember cleaning the classroom We keep/percent/stop him from eating more chips I prefer orange to apple I prefer to walk rather than run I used to sing when I was young What’s wrong with you There have nothing to do with you I am so busy studying You are too young to na?ve I am so tired that I have to go to bed early
《The Kite Runner》追风筝的人--------------------------------美句摘抄 1.I can still see Hassan up on that tree, sunlight flickering through the leaves on his almost perfectly round face, a face like a Chinese doll chiseled from hardwood: his flat, broad nose and slanting, narrow eyes like bamboo leaves, eyes that looked, depending on the light, gold, green even sapphire 翻译：我依然能记得哈桑坐在树上的样子，阳光穿过叶子，照着他那浑圆的脸庞。他的脸很像木头刻成的中国娃娃，鼻子大而扁平，双眼眯斜如同竹叶，在不同光线下会显现出金色、绿色，甚至是宝石蓝。 E.g.: A shadow of disquiet flickering over his face. 2.Never told that the mirror, like shooting walnuts at the neighbor's dog, was always my idea. 翻译：从来不提镜子、用胡桃射狗其实都是我的鬼主意。E.g.:His secret died with him, for he never told anyone. 3.We would sit across from each other on a pair of high
一、翻译 1. The idea of consciously seeking out a special title was new to me., but not without appeal. 让我自己挑选自己最喜欢的书籍这个有意思的想法真的对我具有吸引力。 2.I was plunged into the aching tragedy of the Holocaust, the extraordinary clash of good, represented by the one decent man, and evil. 我陷入到大屠杀悲剧的痛苦之中，一个体面的人所代表的善与恶的猛烈冲击之中。 3.I was astonished by the the great power a novel could contain. I lacked the vocabulary to translate my feelings into words. 我被这部小说所包含的巨大能量感到震惊。我无法用语言来表达我的感情（心情）。 4，make sth. long to short长话短说 5.I learned that summer that reading was not the innocent(简单的) pastime(消遣) I have assumed it to be., not a breezy, instantly forgettable escape in the hammock(吊床)，( though I’ ve enjoyed many of those too ). I discovered that a book, if it arrives at the right moment, in the proper season, will change the course of all that follows. 那年夏天，我懂得了读书不是我认为的简单的娱乐消遣，也不只是躺在吊床上，一阵风吹过就忘记的消遣。我发现如果在适宜的时间、合适的季节读一本书的话，他将能改变一个人以后的人生道路。 二、词组造句 1. on purpose 特意，故意 This is especially true here, and it was ~. (这一点在这里尤其准确，并且他是故意的) 2.think up 虚构，编造，想出 She has thought up a good idea. 她想出了一个好的主意。 His story was thought up. 他的故事是编出来的。 3. in the meantime 与此同时 助记：in advance 事前in the meantime 与此同时in place 适当地... In the meantime, what can you do? 在这期间您能做什么呢？ In the meantime, we may not know how it works, but we know that it works. 在此期间，我们不知道它是如何工作的，但我们知道，它的确在发挥作用。 4.as though 好像，仿佛 It sounds as though you enjoyed Great wall. 这听起来好像你喜欢长城。 5. plunge into 使陷入 He plunged the room into darkness by switching off the light. 他把灯一关，房
The effective sentences:(improve the sentences!) 1.She hopes to spend this holiday either in Shanghai or in Suzhou. 2.Showing/to show sincerity and to keep/keeping promises are the basic requirements of a real friend. 3.I want to know the space of this house and when it was built. I want to know how big this house is and when it was built. I want to know the space of this house and the building time of the house. 4.In the past ten years,Mr.Smith has been a waiter,a tour guide,and taught English. In the past ten years,Mr.Smith has been a waiter,a tour guide,and an English teacher. 5.They are sweeping the floor wearing masks. They are sweeping the floor by wearing masks. wearing masks,They are sweeping the floor. 6.the drivers are told to drive carefully on the radio. the drivers are told on the radio to drive carefully 7.I almost spent two hours on this exercises. I spent almost two hours on this exercises. 8.Checking carefully,a serious mistake was found in the design. Checking carefully,I found a serious mistake in the design.
M1 U1 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： add up (to) be concerned about go through set down a series of on purpose in order to according to get along with fall in love (with) join in have got to hide away face to face 1 We’ve chatted online for some time but we have never met ___________. 2 It is nearly 11 o’clock yet he is not back. His mother ____________ him. 3 The Lius ___________ hard times before liberation. 4 ____________ get a good mark I worked very hard before the exam. 5 I think the window was broken ___________ by someone. 6 You should ___________ the language points on the blackboard. They are useful. 7 They met at Tom’s party and later on ____________ with each other. 8 You can find ____________ English reading materials in the school library. 9 I am easy to be with and _____________my classmates pretty well. 10 They __________ in a small village so that they might not be found. 11 Which of the following statements is not right ____________ the above passage? 12 It’s getting dark. I ___________ be off now. 13 More than 1,000 workers ___________ the general strike last week. 14 All her earnings _____________ about 3,000 yuan per month. 二.用以下短语造句： 1.go through 2. no longer/ not… any longer 3. on purpose 4. calm… down 5. happen to 6. set down 7. wonder if 三. 翻译： 1.曾经有段时间，我对学习丧失了兴趣。（there was a time when…） 2. 这是我第一次和她交流。（It is/was the first time that …注意时态） 3.他昨天公园里遇到的是他的一个老朋友。（强调句） 4. 他是在知道真相之后才意识到错怪女儿了。（强调句） M 1 U 2 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： play a …role (in) because of come up such as even if play a …part (in) 1 Dujiangyan(都江堰) is still ___________in irrigation(灌溉) today. 2 That question ___________ at yesterday’s meeting. 3 Karl Marx could speak a few foreign languages, _________Russian and English. 4 You must ask for leave first __________ you have something very important. 5 The media _________ major ________ in influencing people’s opinion s. 6 _________ years of hard work she looked like a woman in her fifties. 二.用以下短语造句： 1.make (good/full) use of 2. play a(n) important role in 3. even if 4. believe it or not 5. such as 6. because of
English sentence 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能 句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的 句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character.（2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n. 句子：He is in America. 10、appear 出现v. He appears in this place. 11. artist 艺术家n. He is an artist. 12. attract 吸引 He attracts the dog. 13. Australia 澳大利亚 He is in Australia. 14.base 基地 She is in the base now. 15.basket 篮子 His basket is nice. 16.beautiful 美丽的 She is very beautiful. 17.begin 开始 He begins writing. 18.black 黑色的 He is black. 19.bright 明亮的 His eyes are bright. 20.good 好的 He is good at basketball. 21.British 英国人 He is British. 22.building 建造物 The building is highest in this city 23.busy 忙的 He is busy now. 24.calculate 计算 He calculates this test well. 25.Canada 加拿大 He borns in Canada. 26.care 照顾 He cared she yesterday. 27.certain 无疑的 They are certain to succeed. 28.change 改变 He changes the system. 29.chemical 化学药品