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怎样做电动机短路试验?

更新时间:2024-04-24 07:32:46
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Scatteredthroughtheseasoftheworldarebillionsoftonsofsmallplantsandanimalscalledplankton.Mostoftheseplantsandanimalsaretoosmallforthehumaneyetosee.Theydriftaboutlazilywiththecurrents,providingabasicfoodformanylargeranimals.Planktonhasbeendescribedastheequivalentofthegrassesthatgrowonthedrylandcontinents,andthecomparisonisanappropriateone.Inpotentialfoodvaluehowever,planktonfaroutweighsthatofthelandgrasses.Onescientisthasestimatedthatwhilegrassesoftheworldproduceabout49billiontonsofvaluablecarbohydrateseachyear.Thesea’splanktongeneratesmorethantwiceasmuch. Despiteitsenormousfoodpotential,littleeffortwasmadeuntilrecentlytofarmplanktonaswefarmgrassesonland.Nowmarinescientistshaveatlastbeguntostudythispossibility,especiallyasthesea’sresourcesloomevenmoreimportantasameansoffeedinganexpandingworldpopulation. Nooneyethasseriouslysuggestedthat“planktonburgers”maysoonbecomepopulararoundtheworld.Asapossiblefarmedsupplementaryfoodsource,however,planktonisgainingconsiderableinterestamongmarinescientists. Onetypeofplanktonthatseemstohavegreatharvestpossibilitiesisatinyshrimplikecreaturecalledkrill.Growingtotwoorthreeincheslong,krillprovidethemajorfoodforthegiantbluewhale,thelargestanimalevertoinhabittheEarth.Realizingthatthiswhalemaygrow100feetandweigh150tonsatmaturity,itisnotsurprisingthateachonedevoursmorethanonetonofkrilldaily. Krillswimaboutjustbelowthesurfaceinhugeschoolssometimesmileswide,mainlyinthecoldAntarctic.Becauseoftheirpinkcolor,theyoftenappearasasolidreddishmasswhenviewedfromashiporfromtheair.Krillareveryhighinfoodvalue.Apoundofthesecrustaceanscontainsabout460calories—aboutthesameasshrimporlobster,towhichtheyarerelated. Ifthekrillcanfeedsuchhugecreaturesaswhales,manyscientistsreason,theymustcertainlybecontendersasnewfoodsourceforhumans. 1.Whichofthefollowingbestportraystheorganizationofthepassage? A.Theauthorpresentstheadvantagesanddisadvantagesofplanktonasafoodsource. B.Theauthorquotespublicopiniontosupporttheargumentforfarmingplankton. C.Theauthorclassifiesthedifferentfoodsourcesaccordingtoamountofcarbohydrate. D.Theauthormakesageneralstatementaboutplanktonasafoodsourceandthenmovestoaspecificexample. 2.Accordingtothepassage,whyisplanktonregardedtobemorevaluablethanlandgrasses? A.Itiseasiertocultivate. B.Itproducesmorecarbohydrates. C.Itdoesnotrequiresoil. D.Itismorepalatable. 3.Whydoestheauthormention“planktonburgers”? A.Todescribetheappearanceofonetypeofplankton. B.Toillustratehowmuchplanktonawhaleconsumes. C.Tosuggestplanktonasapossiblefoodsources. D.Tocomparethefoodvaluesofbeefandplankton. 4.Whatismentionedasoneconspicuousfeatureofkrill? A.Theyarethesmallestmarineanimals. B.Theyarepinkincolor. C.Theyaresimilarinsizetolobsters. D.Theyhavegrasslikebodies. 5.Theauthormentionsallofthefollowingasreasonswhyplanktoncouldbeconsideredahumanfoodsourceexceptthatitis___. A.highinfoodvalue. B.inabundantsupplyintheoceans. C.anappropriatefoodforotheranimals. D.freeofchemicalsandpollutants.
试题分类: 大学英语六级
Insomecountrieswhereracialprejudiceisacute,violencehassocometobetakenforgrantedasameansofsolvingdifferences,thatitisnotevenquestioned.Therearecountrieswherethewhitemanimposeshisrulebybruteforce;therearecountrieswheretheblackmanprotestsbysettingfiretocitiesandbylootingandpillaging.Importantpeopleonbothsides,whowouldinotherrespectsappeartobereasonablemen,getupandcalmlyargueinfavorofviolence–asifitwerealegitimatesolution,likeanyother.Whatisreallyfrightening,whatreallyfillsyouwithdespair,istherealizationthatwhenitcomestothecrunch,wehavemadenoactualprogressatall.Wemaywearcollarsandtiesinsteadofwar-paint,butourinstinctsremainbasicallyunchanged.Thewholeoftherecordedhistoryofthehumanrace,thattediousdocumentationofviolence,hastaughtusabsolutelynothing.Wehavestillnotlearntthatviolenceneversolvesaproblembutmakesitmoreacute.Thesheerhorror,thebloodshed,thesufferingmeannothing.Nosolutionevercomestolightthemorningafterwhenwedismallycontemplatethesmokingruinsandwonderwhathitus.Thetrulyreasonablemenwhoknowwherethesolutionsliearefindingitharderandherdertogetahearing.Theyaredespised,mistrustedandevenpersecutedbytheirownkindbecausetheyadvocatesuchapparentlyoutrageousthingsaslawenforcement.Ifhalftheenergythatgoesintoviolentactswereputtogooduse,ifoureffortsweredirectedatcleaninguptheslumsandghettos,atimprovingliving-standardsandprovidingeducationandemploymentforall,wewouldhavegonealongwaytoarrivingatasolution.Ourstrengthissappedbyhavingtomopupthemessthatviolenceleavesinitswake.Inawell-directedeffort,itwouldnotbeimpossibletofulfilltheidealsofastablesocialprogramme.Thebenefitsthatcanbederivedfromconstructivesolutionsareeverywhereapparentintheworldaroundus.Genuineandlastingsolutionsarealwayspossible,providingweworkwithintheframeworkofthelaw.Beforewecanevenbegintocontemplatepeacefulco-existencebetweentheraces,wemustappreciateeachother'sproblems.Andtodothis,wemustlearnaboutthem:itisasimpleexerciseincommunication,inexchanginginformation."Talk,talk,talk,"theadvocatesofviolencesay,"allyoueverdoistalk,andwearenonethewiser."It'sratherlikethestoryofthefamousbarristerwhopainstakinglyexplainedhiscasetothejudge.Afterlisteningtoalengthyargumentthejudgecomplainedthatafterallthistalk,hewasnonethewiser."Possible,mylord,"thebarristerreplied,"nonethewiser,butsurelyfarbetterinformed."Knowledgeisthenecessaryprerequisitetowisdom:theknowledgethatviolencecreatestheevilsitpretendstosolve. 1.Whatisthebesttitleforthispassage? [A]AdvocatingViolence. [B]ViolenceCanDoNothingtoDiminishRacePrejudice. [C]ImportantPeopleonBothSidesSeeViolenceAsaLegitimateSolution. [D]TheInstinctsofHumanRaceAreThirstyforViolence. 2.Recordedhistoryhastaughtus [A]violenceneversolvesanything.[B]nothing.[C]thebloodshedmeansnothing.[D]everything. 3.Itcanbeinferredthattrulyreasonablemen [A]can'tgetahearing. [B]arelookeddownupon. [C]arepersecuted. [D]Havedifficultyin advocatinglawenforcement. 4."Hewasnonethewiser"means [A]hewasnotatallwiseinlistening. [B]Hewasnotatallwiserthannothingbefore. [C]Hegainsnothingafterlistening. [D]Hemakesnosenseoftheargument. 5.Accordingtheauthorthebestwaytosolveraceprejudiceis [A]lawenforcement.[B]knowledge.[C]nonviolence.[D]Moppinguptheviolentmess.
试题分类: 专业英语八级
Passage4 Questions 16to 20arebasedonthefollowingpassage: Morethan30,000driversandfrontseatpassengersarekilledorseriouslyinjuredeachyear.Atthespeedofonly30milesperhouritisthesameasfallingfromathird-floorwindows.Wearingaseatbeltsaveslives;itreducesyourchanceofdeathorseriousinjurybymorethanhalf. Thereforedriversorfrontseatpassengersover14inmostvehiclesmustwearaseatbelt.Ifyoudonot,youcouldbefinedupto£50.itwillnotbeuptothedriverstomakesureyouwearyourbelt.Butitwillbethedriver’sresponsibilitytomakesurethatchildrenunder14donotrideinthefrontunlesstheyarewearingaseatbeltofsomekind. However,youdonothavetowearaseatbeltifyoureversingyourvehicle;oryouaremakingalocaldeliveryorcollectionusingaspecialvehicle;orifyouhaveavalidmedicalcertificatewhichexcusesyoufromwearingit.Makesurethesecircumstancesapplytoyoubeforeyoudecidenottowearyouseatbelt.(76)Rememberyoumaybetakentocourtfornotdoingso,andyoumaybefinedifyoucannotprovetothecourtthatyouhavebeenexcusedfromwearingit. 1.Thistextistakenfrom________. A)amedicalmagazineB)apolicereport C)alegaldocumentD)agovernmentinformationbooklet 2.Wearingaseatbeltinavehicle________. A)reducesroadaccidentsbymorethanhalf B)savesliveswhiledrivingataspeedupto30milesperhour C)reducesthedeathrateintrafficaccidentsD)savesmorethan15,000liveseachyear 3.Itisthedriver’sresponsibilityto________. A)makethefrontseatpassengerwearaseatbelt B)makethefrontseatchildrenunder14wearaseatbelt C)stopchildrenridinginthefrontseatD)wearaseatbelteachtimehedrives 4.Accordingtothetext,whichofthefollowingpeopleridinginthefrontdosnothavetowearaseatbelt? A)Someonewhoisbackingintoaparkingspace. B)Someonewhoispickingupthechildrenfromthelocalschool. C)Someonewhoisdeliveringinvitationletters. D)Someonewhoisunder14. 5.Forsomepeople,itmaybebetter________. A)towearaseatbeltforhealthreasons B)nottowearaseatbeltforhealthreasons C)togetvalidmedicalcertificatebeforewearingaseatbelt D)topayafineratherthanwearaseatbelt
试题分类: 成人英语三级
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试题分类: 大学英语六级