对称分量法只能用来解三相正弦不对称电路。

1、正确
2、错误
查看答案
正确答案:

正确

答案解析:

暂无解析

上一题
你可能感兴趣的试题

Whattypesofpeoplewereincludedintheresearch?

A、youngpeopleintheirfirstjob
B、menwhowereworking
C、womenwhowereunemployed

1.Thefailureofahigh-profilecholesteroldrughasthrownaspotlightonthecomplicatedmachinerythatregulatescholesterollevels.Butmanyresearchersremainconfidentthatdrugstoboostlevelsof'good'cholesterolarestilloneofthemostpromisingmeanstocombatspirallingheartdisease.

2.DrugcompanyPfizerannouncedon2Decemberthatitwascancellingallclinicaltrialsoftorcetrapib,adrugdesignedtoraiseheart-protectivehigh-densitylipoproteins(HDLs).Inatrialof15000patients,asafetyboardfoundthatmorepeoplediedorsufferedcardiovascularproblemsaftertakingthedrugplusacholesterol-loweringstatinthanthoseinacontrolgroupwhotookthestatinalone.

3.Thenewscameasakickintheteethtomanycardiologistsbecauseearliertestsinanimalsandpeoplesuggesteditwouldlowerratesofcardiovasculardisease."Therehavebeennoredflagstomyknowledge,"saysJohnChapman,aspecialistinlipoproteinsandatherosclerosisattheNationalInstituteforHealthandMedicalResearch(INSERM)inPariswhohasalsostudiedtorcetrapib."Thiscancellationcameasacompleteshock."

4.TorcetrapibisoneofthemostadvancedofanewbreedofdrugsdesignedtoraiselevelsofHDLs,whichferrycholesteroloutofartery-cloggingplaquestotheliverforremovalfromthebody.Specifically,torcetrapibblocksaproteincalledcholesterolestertransferprotein(CETP),whichnormallytransfersthecholesterolfromhigh-densitylipoproteinstolowdensity,plaque-promotingones.Statins,incontrast,mainlyworkbyloweringthe'bad'low-densitylipoproteins.

Underpressure

5.Researchersarenowtryingtoworkoutwhyandhowthedrugbackfired,somethingthatwillnotbecomeclearuntiltheclinicaldetailsarereleasedbyPfizer.Onehintliesinevidencefromearliertrialsthatitslightlyraisesbloodpressureinsomepatients.Itwasthoughtthatthismildproblemwouldbeoffsetbytheheartbenefitsofthedrug.Butitispossiblethatitactuallyprovedfatalinsomepatientswhoalreadysufferedhighbloodpressure.Ifbloodpressureistheexplanation,itwouldactuallybegoodnewsfordrugdevelopersbecauseitsuggeststhattheproblemsarespecifictothiscompound.OtherprototypedrugsthatarebeingdevelopedtoblockCETPworkinaslightlydifferentwayandmightnotsufferthesamedownfall.

6.ButitisalsopossiblethatthewholeideaofblockingCETPisflawed,saysMotiKashyap,whodirectsatherosclerosisresearchattheVAMedicalCenterinLongBeach,California.WhenHDLsexcretecholesterolintheliver,theyactuallyrelyonLDLsforpartofthisprocess.SoinhibitingCETP,whichpreventsthetransferofcholesterolfromHDLtoLDL,mightactuallycauseanabnormalandirreversibleaccumulationofcholesterolinthebody."You'reblockingaphysiologicmechanismtoeliminatecholesterolandeffectivelyconstipatingthepathway,"saysKashyap.Goingup

7.Mostresearchersremainconfidentthatelevatinghighdensitylipoproteinslevelsbyonemeansoranotherisoneofthebestroutesforhelpingheartdiseasepatients.ButHDLsarecomplexandnotentirelyunderstood.Oneapproveddrug,calledniacin,isknowntobothraiseHDLandreducecardiovascularriskbutalsocausesanunpleasantsensationofheatandtingling.Researchersareexploringwhethertheycanbypassthissideeffectandwhetherniacincanlowerdiseaseriskmorethanstatinsalone.Scientistsarealsoworkingonseveralothermeanstobumpuphigh-densitylipoproteinsby,forexample,introducingsyntheticHDLs."Theonlythingweknowisdeadinthewateristorcetrapib,notthewholeideaofraisingHDL,"saysMichaelMiller,directorofpreventivecardiologyattheUniversityofMarylandMedicalCenter,Baltimore.

Questions7-13

Matchtorcetrapib,HDLs,statinandCETPwiththeirfunctions(Questions8-13)..WritethecorrectletterA,B,CorDinboxes8-13onyouranswersheet.NBYoumayuseanylettermorethanonce.

7.Ithasbeenadministeredtoover10,000subjectsinaclinicaltrial.

8.Itcouldhelpridhumanbodyofcholesterol.

9.Researchersareyettofindmoreaboutit.

10.Itwasusedtoreducethelevelofcholesterol.

11.AccordingtoKashyap,itmightleadtounwantedresultifit'sblocked.

12.Itproducedcontradictoryresultsindifferenttrials.

13.ItcouldinhibitLDLs.Listofchoices

A.TorcetrapicB.HDLSC.StatinD.CETP

CignaInsuranceCompanyoffersemployeestheoptionofplacingtake-outmealorderswiththecompanychef.

Everyyear,about10millionofthe150millionworkersintheEuropeanCommunityareaffectedbyincidents,”accidents”ordiseasesatwork.

FelicityLawrence

ThursdayDecember28,2006

TheGuardian

1.ConsumersaretobepresentedwithtworivalnewyearadvertisingcampaignsastheFoodStandardsAgencygoespublicinitsbattlewiththeindustryoverthelabellingofunhealthyfoods.

2.TheGuardianhaslearnedthattheFSAwilllaunchaseriesof10-secondtelevisionadvertsinJanuarytellingshoppershowtofollowared,amberandgreentrafficlightlabellingsystemonthefrontoffoodpacks,whichisdesignedtotackleBritain’sobesityepidemic.

3.Thecampaignisadirectresponsetoaconcertedattemptbyleadingfoodmanufacturersandretailers,includingKellogg’sandTesco,toderailthesystem.Theindustryfearsthattrafficlightswoulddemoniseentirecategoriesoffoodsandcouldseriouslydamagethemarketforthosethatarefatty,saltyorhighinsugar.

4.TheUKmarketforbreakfastcerealsisworth£1.27bnayearandthemanufacturersfearitwillbeseverelydentedifredlightlabelsareputonpackagingdrawingattentiontothefactthatthemajorityarehighinsaltand/orsugar.

5.Theindustryisplanningamajormarketingcampaignforacompetinglabellingsystemwhichavoidscolour-codinginfavourofinformationaboutthepercentageof"guidelinedailyamounts"(GDAs)offat,saltandsugarcontainedintheirproducts.

6.Thebattleforthenation’sdietcomesasnewrulesontelevisionadvertisingcomeintoforceinJanuarywhichwillbaradvertsforunhealthyfoodsfromcommercialbreaksduringprogrammesaimedatchildren.SourcesattheTVregulatorsarebracedforalegalchallengefromtheindustryandhavedescribedthelobbyingeffortstoblockanynewadbanorcolour-codedlabellingas"themostferociouswe’veeverexperienced".

7.Ofcom’schiefexecutive,EdRichards,said:"Wearepreparedtofaceuptoanylegalactionfromtheindustry,butweverymuchhopeitwillnotbenecessary."TheFSAsaiditwasexpectinganonslaughtfromtheindustryinJanuary.SeniorFSAofficialssaidthemanufacturers’effortstoundermineitsproposalsonlabellingcouldthreatentheagency’scredibility.

8.TerrenceCollis,FSAdirectorofcommunications,dismissedclaimsthattheproposalswerenotbasedonscience."WehavesomeofthemostrespectedscientistsinEurope,bothwithintheFSAandinourindependentadvisorycommittees.ItisunjustifiedandnonsensicaltoattacktheFSA’sscientificreputationandtotrytoundermineitscredibility."

9.TheFSAisunderstoodtohavebriefeditsadagency,United,beforeChristmas,andwillaimtoairadsthatare"non-confrontational,humorousandfactual"asacounterweighttoindustry’seffortsaboutthesametime.Theagency,however,willhaveatinyfractionofthebudgetavailabletotheindustry.

10.GavinNeath,chairmanofUnileverUKandpresidentoftheFoodandDrinkFederation,hassaidthattheindustryhasmadeenormousprogressbutcouldnotacceptred"stop"signsonitsfood.

11.AlastairSykes,chiefexecutiveofNestléUK,saidthatundertheFSAproposalsallhiscompany’sconfectioneryandmostofitscerealswouldscoreared."Arewesayingpeopleshouldn’teatconfectionery?We’redrivenbyconsumersandwhattheywant,andmuchofwhatwedohasbeentomakeourproductshealthier,"hesaid.

12.ChrisWermann,directorofcommunicationsatKellogg’s,said:"Inprinciplewecouldneveraccepttrafficlightlabelling."

13.TherivallabellingschemeintroducedbyKellogg’s,Danone,Unilever,Nestlé,KraftandTescoandnowfavouredby21manufacturers,usesanindustry-devisedsystembasedonidentifyingGDAsofkeynutrients.TescosaysithastestedbothtrafficlightsandGDAlabelsinitsstoresandthatthelatterincreasedsalesofhealthierfoods.

14.ButtheFSAsaiditcouldnotlivewiththisGDAsystemalonebecauseitwas"notscientific"oreasyforshopperstounderstandataglance.

Questions1-6

AnswerthequestionsbelowusingNOMORETHANTHREEWORDSfromthepassageforeachanswer.

1.Whenwillinstructionsbegivenonreadingthecolor-codedlabels?

2.Wherecancustomersfindtheredlightlabels?

3.WhatproblemistheFSAtryingtohandlewiththelabelingsystem?

4.Whichproductsellswellbutmaynotbehealthy?

5.Whatinformation,accordingtothemanufacturers,canbelabeledonproducts?

6.Whatcannotbeadvertisedduringchildren’sprogrammes?

Questions7-13

Usetheinformationinthetexttomatchthepeople(listedA-E)withtheopinions(listed7-13)below.Writetheappropriateletter(A-E)forquestions1-7.

NBYoumayuseanylettermorethanonce.

AEdRichard

BTerrenceCollis

CGavinNeath

DAlastairSykes

EChrisWermann

7.Generallywewillnotagreetousetheredlightlabels.

8.ItisunreasonabletodoubtifFSAistrustworthy.

9.Wearetryingtomeetourconsumers’needs.

10.Thefoodindustryhasbeenimprovinggreatly.

11.Thecolor-codedlabelingsystemisscientific.

12.OurproductswillbelabeledunhealthybytheFSA.

13.Wearereadytoconfrontthemanufacturers.

热门试题 更多>
相关题库更多>
送电线路工
变电检修工
继电保护工
水电自动装置检修工
变电二次安装工
变电一次安装工
配电线路工
试卷库
试题库