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压力容器的最高工作压力是指在正常操作情况下,容器顶部可能出现的最高压力。

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Californiaisalandofvarietyandcontrast.Almosteverytypeofphysicallandfeature,sortofarcticicefieldsandtropicaljunglescanbefoundwithinitsborders.Sharplycontrastingtypesoflandoftenlieveryclosetooneanother.PeoplelivinginBakersfield,forinstance,canvisitthePacificOceanandthecoastalplain,thefertileSanJoaquinValley,thearidMojaveDesert,andthehighSierraNevada,allwithinaradiusofabout100miles.Inotherareasitispossibletogosnowskiinginthemorningandsurfingintheeveningofthesameday,withouthavingtotravellongdistance.ContrastaboundsinCalifornia.ThehighestpointintheUnitedStates(outsideAlaska)isinCalifornia,andsoisthelowestpoint(includingAlaska)。MountWhitney,14,494feetabovesealevel,isseparatedfromDeathValley,282feetbelowsealevel,byadistanceofonly100miles.Thetwoareashaveadifferenceinaltitudeofalmostthreemiles.Californiahasdeep,clearmountainlakeslikeLakeTahoe,thedeepestinthecountry,butitalsohasshallow,saltydesertlakes.IthasLakeTulainyo,12,020feetabovesealevel,andthelowestlakeinthecountry,theSaltonSea,236feetbelowsealevel.Someofitslakes,likeOwensLakeinDeathValley,arenotlakesatall:theyaredrieduplakebeds.Inadditiontomountains,lakes,valleys,deserts,andplateaus,CaliforniahasitsPacificcoastline,stretchinglongerthanthecoastlinesofOregonandWashingtoncombined.

1.WhichofthefollowingisthelowestpointintheUnitedStates?

A.LakeTulainyoB.MojavedesertC.DeathValleyD.TheSaltonSea

2.WhereisthehighestpointintheUnitedStateslocated?

A.LakeTahoe.

B.SierraNevada.C.MountWhitney.

D.Alaska.

3.HowfarawayisDeathValleyfromMountWhitney?

A.About3miles.

D.14,494feet.

4.WhichofthefollowingisNOTmentionedinthepassageasbeingwithinaradiusofabout100milesofBakersfield?

A.ThePacificOcean.

B.SanJoaquinValley.

C.MojaveDesert.

D.OregonandWashington.

5.WhichstatementbestdemonstratesthatCaliforniaisalandofvarietyandcontrast?

A.ThehighestlakeinCaliforniaisLakeTulainyo.

B.ItispossibletogosurfingandsnowskiinginsomepartsofCaliforniawithouthavingtotravellongdistance.

C.SierraNevada,SanJoaquinValley,MojaveDesertandthePacificOceanallliewithinaradiusofabout100miles.

D.OwensLake,inDeathValley,isnotreallyalakeatall.

AsGilbertWhite,Darwin,andothersobservedlongago,allspeciesappeartohavetheinnatecapacitytoincreasetheirnumbersfromgenerationtogeneration.Thetaskforecologistsistountangletheenvironmentaandbiologicalfactorsthatholdthisintrinsiccapacityforpopulationgrowthincheckoverthelongrun.Thegreatvarietyofdynamicbehaviorsexhibitedbydifferentpopulationmakesthistaskmoredifficult:sompopulationsremainroughlyconstantfromyeartoyear;othersexhibitregularcyclesofabundanceandscarcity;stillothersvarywildly,withoutbreaksandcrashesthatareinsomecasesplainlycorrelatedwiththeweather,andinothercasesnot.Toimposesomeorderonthiskaleidoscopeofpatterns,oneschoolofthoughtproposesdividingpopulationsintotwogroups.Theseecologistspositthattherelativelysteadypopulationshavedensity-dependentgrowthparameters;thatis,ratesofbirth,death,andmigrationwhichdependstronglyonpopulationdensity.Thehighlyvaryingpopulationshavedensity-independentgrowthparameters,withvitalratesbuffetedbyenvironmentalevents;theseratesfluctuateinawaythatiswhollyindependentofpopulationdensity.Thisdichotomyhasitsuses,butitcancauseproblemsiftakentooliterally.Foronething,nopopulationcanbedrivenentirelybydensity-independentfactorsallthetime.Nomatterhowseverelyorunpredictablybirth,death,andmigrationratesmaybefluctuatingaroundtheirlong-termaverages,iftherewerenodensity-dependenteffects,thepopulationwould,inthelongrun,eitherincreaseordecreasewithoutbound(barringamiraclebywhichgainsandlossescanceledexactly)。Putanotherway,itmaybethatonaverage99percentofalldeathsinapopulationarisefromdensity-independentcauses,andonlyonepercentfromfactorsvaryingwithdensity.Thefactorsmakinguptheonepercentmayseemunimportant,andtheircausemaybecorrespondinglyhardtodetermine.Yet,whetherrecognizedornot,theywillusuallydeterminethelong-termaveragepopulationdensity.Inordertounderstandthenatureoftheecologist’sinvestigation,wemaythinkofthedensity-dependenteffectsongrowthparametersasthesignalecologistsaretryingtoisolateandinterpret,onethattendstomakethepopulationincreasefromrelativelylowvaluesordecreasefromrelativelyhighones,whilethedensity-independenteffectsacttoproducenoiseinthepopulationdynamics.Forpopulationsthatremainrelativelyconstant,orthatoscillatearoundrepeatedcycles,thesignalcanbefairlyeasilycharacterizedanditseffectsdescribed,eventhoughthecausativebiologicalmechanismmayremainunknown.Forirregularlyfluctuatingpopulations,wearelikelytohavetoofewobservationstohaveanyhopeofextractingthesignalfromtheoverwhelmingnoise.Butitnowseemsclearthatallpopulationsareregulatedbyamixtureofdensity-dependentanddensity-independenteffectsinvaryingproportions.

1.Theauthorofthetextisprimarilyconcernedwith

[A]Discussingtwocategoriesoffactorsthatcontrolpopulationgrowthandassessingtheirrelativeimportance.

[B]Describinghowgrowthratesinnaturalpopulationsfluctuateovertimeandexplainingwhythesechangesoccur.

[C]Proposingahypothesisconcerningpopulationsizeandsuggestingwaystotestit.

[D]Posingafundamentalquestionaboutenvironmentalfactorsinpopulationgrowthandpresentingsomecurrentlyacceptedanswer.

2.Itcanbeinferredfromthetextthattheauthorconsidersthedichotomydiscussedtobe

[A]Applicableonlytoerraticallyfluctuatingpopulations.

[B]instrumental,butonlyifitslimitationsarerecognized.

[C]Dangerouslymisleadinginmostcircumstances.

[D]Acompleteandsufficientwaytoaccountforobservedphenomena.

3.tothetext,allofthefollowingbehaviorshavebeenexhibitedbydifferentpopulationsEXCEPT

[A]Roughlyconstantpopulationlevelsfromyeartoyear.

[B]Regularcyclesofincreasesanddecreasesinnumbers.

[C]Erraticincreasesinnumberscorrelatedwiththeweather.

[D]Uncheckedincreasesinnumbersovermanygenerations.

4.Thediscussionconcerningpopulationinthethirdparagraphservesprimarilyto

[A]Demonstratethedifficultiesecologistsfaceinstudyingdensity-dependentfactorslimitingpopulationgrowth.

[B]Advocatemorerigorousstudyofdensity-dependentfactorsinpopulationgrowth.

[C]Provethatthedeathratesofanypopulationareneverentirelydensity-independent.

[D]underlinetheimportanceofevensmalldensity-dependentfactorsinregulatinglong-termpopulationdensities.

5.Inthetext,theauthordoesallofthefollowingEXCEPT

[A]Citetheviewsofotherbiologists.

[B]Defineabasicproblemthatthetextaddresses.

[C]Presentconceptualcategoriesusedbyotherbiologists.

[D]Describetheresultsofaparticularstudy.

汉译英:暮色中,河湾里落满云霞,与天际的颜色混合一起,分不清哪是流云哪是水湾。也就在这一幅绚烂的图画旁边,在河湾之畔,一群羊正在低头觅食。它们几乎没有一个顾得上抬起头来,看一眼这美丽的黄昏。也许它们要抓紧时间,在即将回家的最后一刻再次咀嚼。这是黄河滩上的一幕。牧羊人不见了,他不知在处歇息。只有这些美生灵自由自在地享受着这个黄昏。这儿水草肥美,让它们长得肥滚滚的,像些胖娃娃。如果走近了,会发现它们那可爱的神情,洁白的牙齿,那丰富而单纯的表情。如果稍稍长久一点端详这张张面庞,还会生出无限的怜悯。

EinsteinwontheNobelPrizein1921andenjoyedgreatfameinGermanyuntiltheriseofNazism____hewasexpelledfromGermanybecausehewasaJew.

AlthoughSPanish,heattendedthecourse.

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