根据下列内容，回答181-185题。 AnneWhitney,asophomoreatColoradoStateUniversity,firsthadaproblemtakingtestswhenshebegancollege."Iwasalwayswellpreparedformytests.SometimesIstudiedforweeksbeforeatest.YetIwouldgointotakethetest,onlytofindIcouldnotanswerthequestionscot-rectly.Iwouldblankoutbecauseofnervousnessandfear.Icouldn'tthinkoftheanswer.MylowgradesonthetestsdidnotshowwhatIknewtotheteacher."Anotherstudentinbiologyhadsimi-larexperiences.Hesaid:"Myfirstchemistrytestwasverydifficult.Then,onthesecondtest,Isatdowntotakeit,andIwassonervousthatIwasshaking.Myhandsweremovingupanddownsoquicklythatitwashardtoholdmypencil.IknewthematerialandIknewtheanswers.Yet! couldn'tevenwritethemdown!" Thesetwoyoungstudentswereexperiencingsomethingcalledtestanxiety.Becauseastudentworriesandisuneasyaboutatest,hisorherminddoesnotworkaswellasitusuallydoes.Thestudentcannotwriteorthinkclearlybecauseoftheextremetensionandnervousness.Althoughpoorgradesareoftenaresultofpoorstudyhabits,sometimestestanxietycausesthelowgrades.Recently,testanxietyhasbeenrecognizedasarealproblem,notjustanexcuseorafalseexpla-nationoflazystudents. Specialuniversityadvisingcoursestrytohelpstudents.Inthesecourses,advisorstrytohelpstudentsbyteachingthemhowtomanagetestanxiety.Atsomeuniversities,studentstaketeststomeasuretheiranxiety.Ifthetestsshowtheiranxietyishigh,thestudentscantakeshortcoursestohelpthemdealwiththeirtensions.Thesecoursesteachstudentshowtorelaxtheirbodies.Studentsaretrainedtobecomecalminverytensesituations.Bycontrollingtheirnervousness,theycanlettheirmindsworkatease.Learnedinformationthencomesoutwithoutdifficultyonatest. AnexpertattheUniversityofCaliforniaexplains:"Withalmostallstudents,relaxationandlessstressarefeltaftertakingourprogram.Mostofthemexperiencebettercontrolduringtheirtests.Almostallhavesomeimprovement.Withsome,theimprovementisverygreat." To"blankout"isprobably___________.
A.to be like a blanket B.to be sure of an answer C.to be unable to think clearly D.to show knowledge to the teacher正确答案C
