当前位置：文档之家 › Prediction of the critical condition for flame acceleration over wood surface with different sample

Prediction of the critical condition for flame acceleration over wood surface with different sample

  • 格式：pdf
  • 大小：618.75 KB
  • 文档页数：4

Brief CommunicationsPrediction of the critical condition for flame acceleration over wood surface with different sample orientationsYing Zhang,Jie Ji,Qingsong Wang,Xinjie Huang,Qiuhong Wang,Jinhua Sun ⇑State Key Laboratory of Fire Science,University of Science and Technology of China,Hefei 230027,Chinaa r t i c l e i n f o Article history:Received 19January 2011Received in revised form 3December 2011Accepted 16April 2012Available online xxxx Keywords:Flame spread InclinationTransition zone AccelerationCritical conditiona b s t r a c tTo understand the inclination effects on flame spread over wood surface,a set of flame spread experi-ments were carried out for different sample orientation angles from À50°to 20°in the Hefei Plain (at the altitude of 50m)and in the Tibetan plateau (at the altitude of 3658m).At both altitudes,a transition zone was found at 10–20°orientation for flame spread rate,the preheated length and flame angle from the horizontal.The transition zone was an external manifestation of the change of flame spread from steady state to acceleration.A new relationship of P c =1was established to predict the occurrence of acceleration based on theoretical analysis.Experimental data at the two altitudes suggested that the crit-ical value of P c is about 1.1–1.2,which has a good agreement with the theoretical value.Ó2012The Combustion Institute.Published by Elsevier Inc.All rights reserved.1.IntroductionFire accident investigations suggested that the inclination of solid surface is one of the most important factors in flame spread,such as the 30°inclination of the wooden escalator in the King’s Cross fire in 1987[1–4].After that,the experiments were carried out to study flame spread over inclined surfaces and the trench effect [5–14].The inclination effects on flame spread [5–10]indicated that the flame spread rate increased with inclination angle in an exponential way.The trench effects on flame spread were explored [11–14],and it was found that fire eruption occurred over an inclined surface with a sufficient steepness,even when the trench side-walls were removed.Drysdale and Macmillan [12]pointed out a transition zone at a sample orientation of around 15–20°.Wu et al.[14]studied the fire plume interaction with an inclined surface using a schlieren system and proposed two parameters to describe the fire plume features:(1)the length of the fire plume attachment to the surface;(2)the flame tilt angle from the inclined surface.They pointed out that the sharp rise in the plume attachment length identifies the critical inclination angle.However,further discussion about the mecha-nism of transition has not been reported so far and the related critical condition of transition has not been addressed yet.In this study,the experiments under inclination angles ranging from À50°to 20°were conducted at two cities:the Lhasa City (in the Tibetan plateau,3650m altitude)and the Hefei City (in the Hefei Plain,58m altitude).The ambient pressures of the two cities are 65.5kPa and 100.8kPa.The flame shape during flame spread were captured by digital video,and the rate of fire spread and the flame heat flux feedback to the unburned surface were also monitored in experiments.The mechanism of the transition zone and the prediction on the critical condition will be discussed in this paper.2.ExperimentsThe experimental facility is described in [15].A color digital video camera was set outside the observation window and the flame spread process was in a real time record.A steel ruler was fixed aside the sample holder,which can be rotated through 360°,to determine the scale of images.A rotary dial,with 2°preci-sion,was mounted on the sample holder to indicate the inclination of sample surface.A heat flux meter TS30was mounted on the sample surface to measure total flame heat flux to sample surface.The meter’s uncertainty is less than 3%,and its operating temper-ature could not exceed 200°C,so it has to be removed away when the pyrolysis front reaches.The inclination angle h of the sample surface is defined as follows:a horizontal sample surface has an inclination of 0°(h =0°);for a surface inclined at an angle a from the horizontal,the inclination angle h equals to a for upward flame spread;for downward,h =Àa .Whitewood was applied in the series of experiments.The samples had 70mm width,3mm thickness,and 400mm length.Parallel lines were marked at 20mm intervals,perpendicular to0010-2180/$-see front matter Ó2012The Combustion Institute.Published by Elsevier Inc.All rights reserved./10.1016/bustflame.2012.04.007Corresponding author.E-mail address:sunjh@ (J.Sun).the direction of spread.Theflame propagated along the wood grain.To eliminate the influence of the wood moisture content, samples were kept in a drying oven at constant temperature of 80°C until their weights kept constant all times.The rate offlame spread was timed by recording the arrival time of the pyrolysis front at each mark by a stopwatch.Then,the mark line locations and their arrival times were plotted and the slope of the linefit represents the rate of spread.Theflame shape was recorded by a digital camera at25frames per second.The characteristic parameters offlame shape are illus-trated in Fig.1.The general model forflame spread over inclined surface(see Fig.1)consists of three main regions:the burnt zone (x b),the pyrolysis zone extending to region x p,and the preheated zone(the region x fÀx p).In our experiments,the pyrolysis zone is defined as the zone on whichflame attaches to the sample surface.The preheat length d f is defined as the sample distance (x fÀx p).Flame tilt angle a is defined as the angle between the unburned surface andflame centerline,which is the line from flame tip to the center point of pyrolysis zone.The angle between flame and the horizontal direction is represented by h+a.it becomes more sensitive to the inclination angle when the incli-nation angle is greater than0°.Figure3shows theflame spread rate at different orientation an-gles.Theflame fails to spread at high altitude if the angle of inclina-tion is less thanÀ32°,and at low altitude,the extinction angle is À45°.The rates at both altitudes increase with an increase of in-clined angle,and the rate at the high altitude is lower than that at the low altitude.At both altitudes,a significant rise in the rate of spread from10°to20°was observed in Fig.3.Similar results were also found in previous experiments using PMMA samples[12]. 3.2.Discussion on the transition zoneIn this study,two parameters are measured from the video information:the preheated length(d f)and theflame angle from the horizontal direction(h+a),and the results are shown in Fig.4.A transition zone around10–20°can be observed in thefig-ures of the preheated length and the angle as a function of sample orientation at both altitudes.The preheat length shows a slight rise from h=0°to h=10°,but a further increase in the inclined angleα1x2Flame heatflux to unburned surface under different inclination at altitudes.3.Flame spread rates on plateau and plain as a function of orientation[12]Fig.4.Flame angle from horizontal direction and preheated length as a function of orientation at both altitudes.Figure 5shows the time evolution of the pyrolysis front position at two altitudes.The movement of the pyrolysis front has signifi-cantly different behavior at the angles of 0°,10°,and 20°.The posi-tion of pyrolysis front moves linearly with time at h =0°and 10°.For h =20°,the position of the pyrolysis front moves exponentially with time,which implies that the flame spread rate accelerates.Based on the analysis on the preheat length,the angle h +a and the flame spread rate,the mechanism of the transition zones around 10–20°could be explained as follows.Firstly,the interac-tion between the flame and the inclined surface is changed due to the Coanda effect,which is a response to the pressure differential induced by differences in the capacity for entrainment of air ups-lope and down-slope of the fire plume [16,17].Thus,the fire plume attaches to the inclined surface.The flame attachment is observed from the sharp drop of the angle h +a :at the inclined angle of 0°and 10°,both of the angles h +a at the two altitudes almost equals to 90°,which indicates that the flame is mainly influenced by buoy-ancy and remains in the vertical direction.Once the inclined angle exceeds 10°,the interaction between the flame and the unburned surface becomes significant and the angle between them decreases sharply.Then,the tilted flame is close to the inclined surface and can result in the enhancement of heat transfer from the flame to the unburned surface,which is indicated by the sharp rise of the preheated length.The flame spread changed from steady-state to acceleration due to the change of the heat transfer process (see Fig.5).Therefore,the transition zones reflect the change in flamedepends on the heat flux over the visible flame extension and is roughly constant [19].Therefore,t f does not vary with time in the flame spread process.From Eq.(1),we know the critical condition of flame acceleration is:d v p dt ¼d d f dt ¼d ðx f Àx p Þdt¼0ð2ÞFor upward flame spread over an inclined surface,fires will quickly become turbulent.In our experiments,turbulent flame were found after flame spread for 100mm at both altitudes even at h =0°.Quintiere [19]suggested an empirical formula to predict the length of turbulent flame spread over solid surface with an in-clined angle h :x f ¼1:02l cY o 2;1ð1ÀX r Þ1=3ð3Þwhere Y o 2;1¼0:233is the ambient oxygen mass fraction,and X r is the flame radiation fraction,which means the ratio of heat from flame radiation to heat released by fuel combustion.In general,X r %0.1.The convective plume length scale l c is a function of x p :l c ¼_q 00f D h c x pq 1c p T 1L ffiffiffiffiffiffiffiffiffiffiffiffiffiffig sin hp !2=3ð4Þwhere T 1and q 1are the ambient temperature and the air density in ambient condition,g is the acceleration due to gravity,9.8m/s 2,Table 1Some key characteristic parameters of flame shape.h (°)High altitudeLow altitudea (°)h +a (°)d f (mm)x p (mm)a (°)h +a (°)d f (mm)x p (mm)082±882 2.3±0.822981±981 5.1±1.26471072.5±17.582.512.6±2.374972±188215.7±4.32552029.4±2449.4110.4±33.86543±476393.4±1.38.685Fig.5.The time evolutions of pyrolysis front position under different inclinations:(a)at high altitude;(b)at low altitude.Y.Zhang et al./Combustion and Flame xxx (2012)xxx–xxx3P ¼1:8ð1À1=c Þðp 1Y 3=2o 2;1Þð1ÀX r Þ1=2ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffix p g sin h p _q 00f D h c =Lð6ÞOnce P exceeds 1,the acceleration of flame spread occurs.Therefore,the semi-empirical formula of P c ,th =1is postulated to predict the occurrence of acceleration.Moreover,the P number can also be calculated from our experimental results,and the calculated results are presented in Fig.6.As observed at both altitudes,the transition occurred around 10–20°,so the critical dimensionless number P c ,ex obtained in our experiments is in the range of 1.1–1.2.The experimental result of P c ,ex %1.1–1.2is consistent with the theoretical value of 1,which also suggests that the present theoretical analysis is reasonable.4.ConclusionsIn order to explore the inclination effects on flame spread over a wood sample surface,experiments with various sample orienta-tions were carried out in the Tibetan plateau and the Hefei plain.Some key characteristic parameters of flame spread were analyzed,such as the flame heat flux,the rate of spread and the flame shape.The main conclusions are summarized as following:(1)At both altitudes,the flame heat flux,and thus the flamespread rate increase with the inclined angle.A transition zone of the flame spread rate was found when the angle of inclination ranged from 10°to 20°.for the Doctoral Program of Higher Education of China (No.20113402110023).The authors gratefully acknowledge these supports.References[1]D.Fennel,Investigation into the King’s Cross Fire,HMSO,London,UK,1988.[2]S.Simcox,N.S.Wilkes,I.P.Johnes,Fire at King’s Cross Underground station,18th November 1987:Numerical Simulation of the Buoyancy Flow and Heat Transfer,Report No.AERE-G 4677,Harwell,UK,1988.[3]K.Moodie,Fire Saf.J.18(1992)13–33.[4]A.F.Roberts,Fire Saf.J.18(1992)105–121.[5]J.G.Quintiere,Fire Saf.J.6(2001)291–312.[6]A.Beswick,Conducting Classic Fire Experiments as a Showcase of Fire SafetyEngineering,MEng Project Thesis,University of Edinburgh,2009.[7]A.Ito,Y.Kudo,H.Oyama,Combust.Flame 142(2005)428–437.[8]A.Ito,T.Kashiwagi,Combust.Flame 71(1988)189–204.[9]M.J.Gollner,F.A.Williams,A.S.Rangwala,Combust.Flame 158(2011)1404–1412.[10]A.S.Rangwala,A.Steven,G.Buckley,et al.,bust.Inst.31(2007)2607–2615.[11]D.A.Smith,Fire Saf.J.18(1992)231–244.[12]D.D.Drysdale,A.R.Macmillan,Fire Saf.J.18(1992)245–254.[13]Y.Wu,D.D.Drysdale,Study of Upward Flame Spread on Inclined Surfaces,HSEContract Research,Report No.122/1996,1996.[14]Y.Wu,H.J.Xing,G.Atkinson,Fire Saf.J.35(2000)391–403.[15]Y.Zhang,J.Sun,J.Ji,et al.Fire Saf.J.doi:10.1016/j.firesaf.2012.02.006.[16]J.Sharples,M.Gill,J.W.Dold,The trench effect and eruptive wildfires:lessonsfrom the King’s Cross underground disaster,in:Proceedings AFAC 2010,2010.[17]J.W.Dold,Flow attachment in eruptive fire growth,in:VI InternationalConference on Forest Fire Research,2010.[18]J.G.Quintiere,Fundamentals of Fire Phenomena,John Wiley &Sons,TheAtrium,Southern Gate,Chichester,UK,2006.p.196–202.[19]J.G.Quintiere,Fundamentals of Fire Phenomena,John Wiley &Sons,TheAtrium,Southern Gate,Chichester,UK,2006.p.207.Fig.6.The dimensionless parameter P as a function of inclination.。

合集下载

翻译入门_练习题参考答案

翻译入门_练习题参考答案

Ex. 1Translate the following into Chinese.●It is for us, the living, rather, to be dedicated here to the unfinished work which theywho fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us: that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion; that we here highly revolve that these dead shall not have died in vain; that this nation, under God, shall have a new birth of freedom; and that government of the people by the people and for the people shall not perish from the earth.●毋宁说，倒是我们这些还活着的人，应该在这里把自己奉献于勇士们已经如此崇高地向前推进但尚未完成的事业。

倒是我们应该在这里把自己奉献于仍然留在我们面前的伟大任务——我们要从这些光荣的死者身上汲取更多的献身精神，来完成他们已经完全彻底为之献身的事业；我们要在这里下定最大的决心，不让这些死者白白牺牲；我们要使国家在上帝福佑下得到自由的新生，要使这个民有、民治、民享的政府永世长存。

.Ex. 2●Translate the followings from English into Chinese or from Chinese intoEnglish.● 1. He became an artist after a fashion.●他追求时尚成了一名艺术家。

英语句子成分解释(主谓宾定状补同位插入语) 1

英语句子成分解释(主谓宾定状补同位插入语) 1


02
Subject
Definition of Subject
The subject is the person or thing performing the action of the verb in the presence It is the focal point of the presence, and without it, the presence would not make sense
Pronoun subject
The subject is a pronoun, such as "he," "she," "it," or "they."
Gerund subject
The subject is a presentation particle or gerund, such as "running" or "swimming."
In English, it is common to place the predicate at the end of the sentence, specifically in formal writing and speech This placement helps to maintain the flow and coherence of the presence
reason for the existence of the presence
The type of predicate
Simple predict
Compound prediction
Complex prediction
高教社中职英语基础模块1unit课件

高教社中职英语基础模块1unit课件

03
Guidance and Practice of Listening Skills
01
Provide feedback on listening performance: After students complete the listening tasks, provide feedback on their performance, pointing out areas for improvement and highlighting good practices
01
02
03
04
Learning objectives and requirements
Basic vocabulary and expressions related to vocal topics
Common language structures and functions used in verbal English
01
02
Practice listening skills
Design listening activities that allow students to practice their listening skills, such as gap filling exercises, multiple choice questions, or true/false statements
Unit theme and background
Objectives
To develop basic English language proficiency in speaking, listening, reading, and writing
电力工程师英语题库答案(自己整理)

电力工程师英语题库答案(自己整理)

单选题"Smooth"here means clam100 words in which to sum up his speecha body learns to creep before it learnsa career appeals to manya dictionary at handa german accenta Japanese custom to take offa pickpocket robbed her of her moneyabout five hundred workers inaccuracy is fundamental to theafter a heated debateall indignant at eht injusticeall that matters to meall that matters to me for theall the desks in the room are covered with dust all the heated arguments they hadalways busy with the houseworkalways room for improvementamerica by satellite and was heardamerican blacks were denied equal rightsan advantage over others inan desperate man will stopan expert at making himselfand could cave in at any timeand didnt check in at theirand fell behind in her lessonsand then leveled off at 25000anything that runs electricity with your wetare most considerate of the patientsare often as good as or betterare really running a riskargument was inevitable because theyarmy had to retreat hastilyas biographies to fiction fo anyas possible in order to repay jennieas winter gave way to springasked to check out five hoursat the end the score was Argentina 3 attention to generation gap for itBaby-sitting is part of anback to a deliver a seriesbad as had been paintedbased on derived from an oldbathroom burned out and fatherbe generous with his money be so critical of its spendingbecame famous overnightbecause brakes failedbecause i stayed up late lastbecause im on holidaybecause technology is changing go rapidlybest candidate to carry out the planbig plant account for one thirdbig plant account for one third of allblacks were denied equalbodys vital organsboring but by and by i findbranch stuck out and caughtbrenda disposed of the housebridge has been held up bybrilliant but at all events he workedbuild that factory so as not to make the water dirty building about thirty feet highbut also supplies steam to heat usersbut at any rate it wasbut kept back the bitbut sand as far as webut the medicine pulled her throughbut they were still 12000 dollars short fot the project by the year 2000he had worked in the powerby way of an excusecall you up last nightcall you up last nightcame into power he changedcamping facilities include acan always come up withcan best handle the problemcan is now on sale for ten centscan learn huge amouts of informationcan make friends wiht her socan stand the test of timecan still remember us walking hand in handcan work up the feeling ofcan you spare a minute for mecarbon is an element while carboncarbon is an element while carbon dioxidecare for trees in proportion the many benefits change was so gradual that we hardlycheered and made way for himchildren are very curious by naturechildren lood up to older oneschina is famous for the great wallclimb though rather steepercome and keep me companycompany he in charge of itcompany hes in charge of itcomplicated problems but can be solved considering his ageㄛhe is unableconstrution is held once a weekcontrary to you predictioncould get by wiht the minimumcould you tell me when the negotiation will begin could you tell me who she iscouldnt help worrying about hercountry population improving fastcurious by naturecustoms were handed down from father to deeds are worthy of being praiseddespite all the heated arguments they had dictionary is indispensable to the studydid it out of gratitude fordidnt live up to what haddiffer with us in terms of certaindifficult for us to treat the faultdifficulty in learning englisg atdisapproved fo the way hedistribution equipment locationit candoctor sat up all nightdoesnt permit smoking in classdog was run over by a busdone is open to criticismdont know how to do itdont make fun of hershe is in tearsdont quarrel about small thingsdouble room available nowdrew to a close late ineach electron has a negative chargeeasy to rid oneselfelectricity needs conductors like metal elephant fell into the trap the hunters hadelse and get down to itelse and get down to itend reason prevailedengineer zhou has learned english for five enjoy yourselves children motherevents will pay you backever catches sight of the mugger ever to shakd off israelievery confidence in his secertary everyone seemed to turn a blind examination is fatal to the planexcuse memay I haveexpected you to turn up at the morning exploded will have to compensate the loss facing fierce competitionfar from admiring hisfast and soon overtake other carsfeeling are mutualfind a large enough coat and sofind a way to solve itfirm would transfer him tofollowed by his studentsfor all his knowledgefor there are few mistakes infor trees in proportion to the manyfor what reason did she quarrelford hall in memory offorward to meeting the greatfot the sake of the childrenfou your help its very valuablefour years since he leftfriendly cordial atmospheregenerator must be kept clean every day getting on with her studygettysburg adderss by heartgirl was isolated fromgive the boy a pat on the back once in given her their consentgiven their inexperienceglad to have been given a chancceglass will crack if you pourgo and bring a tin of lubricating oilgo out for a walkgood deal of trial and error in making good work deserves good paygoods at all costsgovernment had granted them government will offer us whatgreat delight in collecting stampsgreat sympathy for the poorgrown up should be responsiblehad a heated discussionhad been paintedhad every confidence in his secretaryhad much to be thankful forhad to settle for $100hair is also characteristic of swedishhanded down to the oldesthard outside and John was too anxious to gohas been vacant ever sincehas marked a new era in the historyhave a meeting another dayhave a table to himselfhave been on the declinehave much in commonhave my car repaired tomorrow morninghave no taste for ithave put on a poundhave the pleasure of yourhave to compensate for the losshave to go by the ruleshave to go without themhave to hurry up this job ifhave to say refers to all of youhave to step up productionhave to step up productionhave you heard about Mr.Johnsonhe came face to face with a newhe came home with safetyhe has a peculiar habit ofhe has been studying the problem in his study for a he has kept up a correspondencehe is going to the hospital tohe is on intimate terms withhe lay awake all nightthinking over the problemhe left blanks for allhe left blanks for all thehe left his mobile phonehe left out an importanthe rose early the nextthe river had risen one feethe shot at the birdhe succeeded reaching the castle but failed to find the heart is set on beingheart stopped beating just whenheld their breath as the twoher again beford longher family sympathized with her desirdher mind to get rid of her badher she let them down hes taken to drink andhigh school graduated 300 studentshigh time he bought a new onehim under great stresshis adventures makes excellenthis ambition had alwayshis ambition had always beenhis best to relieve her ofhis debts confirmed their suspicionhis father paved the way for himhis fatnese renders him unablehis leg.as a result he would havehis speech he referred to the greathis speech he referred to the greathis total income of a yearyearly income totals $500.it reached a total ofhome on condition that he remainedhonesty is out of questionhouse with a view to buyinghow about staying at hoomhow id react to a situationhow is he justified in blaminghow magenificent the changjianghow that had come abouthow you present yourself on paperhundreds of students attendedhusband for the sake of the childrenhusband wasn＊t content with whati am tired of your stupid conversationi an tired for your stupidi couldnt find a large enough coat and ao ii happened to see him ini have always considered you myi heard her talking about whom i had never heard ofi hope it will clear upi long for an oppotunityi often mistake Tom for hisi prefer staying at home to playing outsidei ran across her in the publici received the inventation to the on idea if i should accept iti recognized him the momenti recommended buying this dictionaryi speak for my colleaguesi took your pen by mistakei tried to remember to put everything in good i sometimes forgot to do soi was ashamed of when i livedi would rather have nooddles thani would rather he came tomorrowid like to lend you me electrical engineering handbookbut youd better not lend it to othersif mary is aware of allif you check you paperIll make it workim out of practiceimportant to stare at somebodyimprove his spoken Englishhe practiced talking toimprove the housingin any doubt about whatin contrast to his brotherin such a hurryin the desert felt thirsty.suffered from thirstin the past decadethe installed capacity of generatingin the past decadethe installed capacity of generating unitsin the preaface to this bookin their power for dorothyindustrial countries consume a greatintegration and a third opposesintends to replace the secretaryinterfere with healthinto a passion when he learnedinto the trap the huntersis always respectful to older peopleis as transparent as glasssheis much inferior to th oneis pacing back and forth in his cageis said to cause many peopleIsnt Jane here yet-No much to my supriseshe is lateit is a personal taste whetherit is considerate of you toit is only imaginaryit is ture that light travels faster than soundit looked as good as newit on purposeit seems that he wasit should cure my coldit took millions of peopleit was in greece that olympicit was natural that he count the daysit would not have taken us so long toits brakes failedits good for you to its important for us to keep the air clean its not quit certain that he willits out of my reach. I need someoneits starting raining ;we had betterits up to us to givejennyi insisted on her comingjob was to sort out the goodjohn regretted not going to the meeting john regretted not going to the meeting johnson has turned down injury must weigh the evidencdjust drop in for a chatjust hanging abuot waiting forkind and helpful to othersknew how to copy wiht an emergency know all the circumstancesknow how to set about itlamp gave poor light.we could language from nonelanguage from scratchlearning habits a(n) average student learns to creep beforeleave quietly so as not to disturbleave the laboratory until the test ended left the tap on for the waterleft the tap on for the water waslessons every day except on Sundaylet anger get the better of his good sense lets go through the roomletters have to be folded several times libyan demonstrators set fire to the us light music when a thunderlikes wearing boots at hoomlittle girl caught her breathliving is rising againlong time to get over grieflook after the childrenlook back into history andlook back on my stay inlook out that steplose heart in time of difficultieslowest layer of the atmosphere machine to convert mechanical energy machine to conwert mechanicalmade up his mind not tomake a noise scolding their childrenmake a sacrifice to get whatmake yourself heard and understoodmanager will reply to all the lettersmany new opportunities will bemany new opportunities will be openedmarked a new era in the historymathematical geniusmay gradually suffer from amay safely conclude that he isme nothing in returnmeeting broke up at midnightmeeting drew to a close late in themeeting is a friend of minemembers objected to having amidnight.why not go to bedmilk easily gose bad in hotmind so constantly that nomoment she was at a loss for wordsmoney put aside for a rainymost of the members objected to having a matchmother asked after you howmother had a taste of the it was tastymr liu has got an important meeting to attendmr wang is the busiest man in our substationMrs.White puts on her coatms chang doesns look well today.what ismust accept the consequencesmust count up how muchmust have done it on purposemust not on any account play withmust send for the plumbermust take on more workersmust take on more workersmust you persist in makingmy cousin submitted hismy job is to organizemy lessons on the radio when she calledmy shoes shined just beforenamed in honor of the first presidentnaughty boy is troublesomeand he is a great trouble to his parentsnear-sightedalmost helpless without glassesnerasighted almost helpless withoutnever completely take the place of humansnever cruel either to people or to animalsnever trouble trouble until trouble troubles you new job smoothed away his worrynewspaper article thorws some light on the situationnext week i will fly to usa to attend an important meetingnext week when they wontnice person to be sure but notno easy method to physicsno im afraid it isnt.youve got theno one queetioned his theoryno sooner had i got hoom than it begannobody was in any doubt about whatnoshow me some othersnot familiar to menow repeat the wordsnursing brought him throughoceaniais a separate landmassbut it is separatedof a poem caugth his eyeof the rapid pace of modern lifeold man devoted himself to teaching forold man held on to his jobon the spotonce you understandone Japanese has 30.6one of the tallest TV towers is the worldonly by accident that youopen letter in answer to the readersother boys made fun of himout problems much faster than humanover so extensive an areaoverweight lady to cut out meatparents couldnt get through to himpeople had lined up in frontperformance testing though it waspernit smoking in classpersuade me of his sincerityphonewhen all along the lineplaced an order withpoor quality goods wont sellpower plant is driven by steamprice of houses is going up while that of cars has been brought downproducts can serve as rawpromised to keep me informed of how ourprotection the emission of dustpumps aur widely used inquite different from chineserailway in association with anotherrailway in association with another companyrailway station in the hope of catchingrain stopped did the sports meeting start againrains are threatening to floodrains are threatening to floodreactions are bound to proceedreactions are bound to proceed smoothlyreading about the adventures of the greatrealized by all meansrepairing myselfbut thank you all the samerepairing the boiler none of them wouldreported approximately over 1000representative to attend to their businessrestricts himself to smoking tworeunion was at my sisterreunion was at my sisters weddingruth finally managed to findsaves energy by operatingsaves energy by operating on twosecondhand car at the price 500seeing that nobody wasshe could pass for 25she has borne him sixshe held back not knowing whatshe inherited a large amountshe is afraid to run a riskshe killed two birds with one stoneshe suffers from stomachachesshe went on read todays newspapershoes are made by handshopkeeper is facing fierce competition from supermarkets should not make so many mistakeshows no respect for at this rulessince you have to stay hoomsinger and in a way he is justifiedsitting on the stdpscrying bitterlysmall piece of ground when ismallpox left lasting scars on most artists kindly left out the pockmarkssmiths are too protective towards theirsmoking will affect his healthso much but were sold out quicklyso we often associate egyptsoldiers are on duty guarding thesoldiers hurried in search of thesome artificial flowers some people reveal qualitiesspent years researching into the effectsspent years researching into the effectsspy on" here means watchstamps in exchange for twostand in a queue fot hoursstation was built 50 years agosteps crying bitterlystood theresurrounded by a lot of peoplestop being creative as soon assuccess is that he workedsuccess only stimulates her to makesuch a handsome young mansupplies thme with food andsupport given in the form of scholarshipssurego down the street and turn left at the first crussing switchgear must be finished in two hourstake it easy we have got plentytake your time.there istaller than any other boy inteachers are trained in the training collegetechnicians are interested in the interesting introduction of test he filled out an applicationthanks to his expertthat he has something important about bolierthat he shouldnt be a bad manthat we should let him go that i hardly had timethat it is beyond all praisethat men are physically strongerthat we should have another talkthe actual process by whichthe are hurting my feetthe best authority on englishthe boiling point is 100the boiling point is 100the boy cheated his friendthe boy cheated his friend outthe boy seated there isthe building remained mostly undamagedthe candle went outthe case contained a lot of things, including a secend-hand the city is named after the famousthe company puts out 13 newthe conference in personthe curtain caught fire andthe custom goes back to thethe doctor sent for will arrivethe earth include ironleadthe eggs laid by the hen were laid in thethe engineers were attending a technical presentationthe experiment in spite of her so muchthe factory are provided with protectivethe gas cut off,i coulentthe girl caught stealing and letthe inspector started off wiht a commentthe judge sentenced the burglarthe jury must weigh the evidence before theythe meeting in place of the presidentthe most efficeient secreatary ivethe most uptodate equipmentthe museum just to find a shelterthe official documents concerning thethe old photo reminded him ofthe parents got in touch with their lostthe photo hanging on the wallthe plane to while away thethe policeman saved the childrenthe policeman searched the prisonerthe power plant was built in 1990the pox wiped out the populationthe pull of gravitythe rains have startedthe rapid pace of modernthe rapid pace ofmodernthe rated output of our newthe roofs of the cottages were covered with leavesthe same substance in differentthe school salute the flagthe sentence was ten yearsthe sisters differ in their intereststhe soldier was badly hurtthe soldiers were stationed at the borderthe sound of voices which we had heardthe sports meeting was to be heldthe story and helped himself tothe team is the best in the countrythe team are training hard for the comingthe terrorists threatened to blowthe town erected a monumentthe train is timed to arrive at 6the two sisters shared one bedthe underlinde part means wasnt able to the underlined part means almost notthe very factorythe woman I came across yesterdaythe workers were exposed to considerable dangerthe worst disaster ever to hittheir house on firethere are quite a few new magazinesthere are two score eggs inthere are various techniques that have to be learntthere have been great changes inthere is too much cream on the cakethere were quantities of rainthermometers are used for temperature measurementthey are queuing up to buythey didnt lose heartthey don＊t get along wellthey had much to be thankful forthey had to send away for manythey met with an accidentthey spent a large amount of money onthis chimney is as high as that onethis is the very house in whichthis young man is twenty years oldthose in favor of the proposalthousands of stars in the skythrough our dry hair the comb andthrough the strait between the two islands and went straight thunder strikes is called lightning arrestorticket is valid for tento be folded severalto be honest i didnt agreeto Beijing scores of timesto bring down the coststo communicate resulted in the high divorceto get enough proteinto hang on until helpto house to fetch her umbrellato keep me informed fo how ourto keep off fattening foodsto know in advance what will happento pass on their technicalto show off your greaterto take revenge on the shirtto visit me every now and thentom lay awake alltoo protective towardstook a glance at her watch andtook no part in the discussiontouched on many pointstrains gave way to electrictrains running on time intransfer is conduction convectiontree and couldnt get downtrial running was over we wenttried in vain to accounttried to confine our conversationturbine must be kept clean erevy dayturbine must be recorded during trial operation underlined part means after thatunless you go by natureuntil next week when they wont beup trade barriers againstused to change the voltage of thevague idea of what was goingvery bad image becausevery strict with herself in her workwaiting for us for some timewalking along the sands towardssaw in the sand the mark wang always comes up with wonderful ideaswas a mathematical geniuswas arriving in half an hourwas extensively damaged in thewas let off with a finewas only too willing towas pulling outwas slow in learningwas slow in learning to readwater and ashwe can at best do only halfwe have run out of sugarwe hold out for anotherwe left off last timewe listened carefully bur heard nothingwe may safely conclude that he iswe should be careful when wewe should take our turn at sitting upwe substituted red ballswe took off so smoothlywe took up a grammar lessenweather was rather worse thanwelcome to beijing mr li said towent back to a deliver a series lectures were already sitting on tablewere called on to take up the struggle forwere eagerly looking forward to the partywere some artificial flowers on thewere talked about yesterdaywerent friendly to themwhat her reaction to the newswhat is the pricewhatever you decidewhatever you decide to take upwhen it is in seasonwhen you go on holidaywhere is my pocket computer-here it is.where shall i get off the trainwhich is heavier iron or copperwhich to sum up his speechwho can tell what will happenwho was in change of the projectwill all those in favor of the propsalwill have plenty of time towill have to do withoutwill you please see to itwist to withdraw from the examinationwith him for some time next weekwith only partial successwith that of the boilerwith that of the steam turbinewoman is too feeble to crosswomen passed outwont escape being punishedwordmen just marken timewords are wrongly spelledhe spelled the words wrong work is often considered to beworld out shrink in the washwould come to so muchwould go after ti with a singlewould rather stay alone in classroom playwould stop calling him a littlewould you mind if i use your dictionary go ahead woule you mind me using your calculatoryet she aimed high her friends spoke highly of her yong man has conquered his fear ofyou are not allowed to fly kite near theyou are very lucky because you haveyou can consule different kindsyou can consult differentyou can rub out pencilyou can take a taxi instead of walking thereyou dont give off smoking youllyou had better not drink water that is not boiledyou hair needs to be cut would you like me to do it for you you have guessed it.you must face up to the problemsyou please do me a favoryou run off 200 copiesyou should allow for delays causedyou should put your mind into ityou will next keep it cleanyou would have some idea how i feelyoud better deposit the moneyyoull end up getting burntyoull start working to the jobyoung people are keen on goingyour answer satisfied her so much was very satisfied your appetite for dinneryour car repaired at onceor youyour teacher in case of difficulty短文判断：1.According to the modeBase on energy conversion,√A power plant tries to×The power plant generation√A power net plan for short×Two important factors for ..√Environmental protection×Water sources ang transportating ×The total capacity in a newly√The number of units exceeds .×The ranks of capacity should be .√2.Among the criticisms of the obamaThe obama administration’s bank…×The word “float”means …×According to the author …√The bailout plan is so complex…×The last paragraph indicates…√3.Australia is a vast continentAustralia is a large country and …×The majority of people living in….√The delivery of education…×The attempt to provide educational….√The schoolwork was delivered…×4.Biomass is a cost-effectiveAs a source of energy…√One of the advantages of…√Biomass doesn’t produce…×Despite its advantages…√Only trees and crops can be…×5.Electrcity may be dangerousElectricity is not dangerous ×Dry wood can carry electricity ×Conductors like metal or what√Human body is a good conductor ×You can use a hairdryer far √Wet hands sre good conductors √The best tool to push a shocked √6.Marx once quoted a famousThe work Capitalism is√For 20% profit ,capital will×For 100%,capital dares √For 200%,capital dares to×The pursuit of profit forces human √The pursuit of profit is much ×There are two ownerships √Only bright manufacturer ×7.Nuclear power’s danger to healthThe mystery about nuclear radiation …√We cannot sense radio activity…×Common radio waves are harmless …√Even at the lowest levels …×Victims of nuclear radiation may…√8.Optical fiber communicationA kind of information√The composite fiber groud wire×One of the transmission tasks√Opical fiber commuication√Large capacity of communication×The communication capacity of optical×The carrier frequency of power√The carrier frequency of microwave is between×The main problem of the fiber√The cables made by×9.Taking a general viewThe 1000MW grade high-efficiency √The temperature of main steam and×The tube wall temperature of √The anti-high temperature steam√The anti-high temperature fluen×The temperature limited of T91 …593.√The temperature limited of T92 …620.×The temperature of austenite steel...650.√The temperature limited of austenite…700.×Only heat-resisting steel can be .×10.The condenser is aA condenser is heat exchanger√It is sggested that the water should√The saturation temperature would not×It is unnecessary to reduce×The condenser does not control×The important facor controlling√The temperature of cooling water will√The temperatur dififference means the√The temperature increase of the cooling×The exhaust steam temperature does not×11.The high voltage circuitContactors,are-exitinguishing elements√The insulation srructure√The are-exitinguishing medium×An oil circuit breaker√A vacuum circuit breaker×A pure SF6 gas×。