题目内容：
根据以下材料，回答题AnneWhitney,asophomoreatColoradoStateUniversity,firsthadaproblemtakingtestswhenshebegancollege."Iwasalwayswellpreparedformytests.SometimesIstudiedforweeksbefore
atest.YetIwouldgointotakethetest,onlytofindIcouldnotanswerthequestionscor-rectly.Iwouldblankoutbecauseofnervousnessandfear.Icouldn'tthinkoftheanswer.MylowgradesonthetestsdidnotshowwhatIknewtotheteacher."Anotherstudentinbiologyhadsimi-larexperiences.Hesaid:"Myfirstchemistrytestwasverydifficult.Then,onthesecondtest,Isatdowntotakeit,andIwassonervousthatIwasshaking.Myhandsweremovingupanddownso
quicklythatitwashardtoholdmypencil.IknewthematerialandIknewtheanswers.YetIcouldn'tevenwritethemdown!"
Thesetwoyoungstudentswereexperiencingsomethingcalledtestanxiety.Becauseastudentworriesandisuneasyaboutatest,hisorherminddoesnotworkaswellasitusuallydoes.The
studentcannotwriteorthinkclearlybecauseoftheextremetensionandnervousness.Althoughpoorgradesareoftenaresultofpoorstudyhabits,sometimestestanxietycausesthelowgrades.
Recently,testanxietyhasbeenrecognizedasarealproblem,notjustanexcuseorafalseexpla-nationoflazystudents.
Specialuniversityadvisingcoursestrytohelpstudents.Inthesecourses,advisorstrytohelpstudentsbyteachingthemhowtomanagetestanxiety.Atsomeuniversities,studentstaketeststo
measuretheiranxiety.Ifthetestsshowtheiranxietyishigh,thestudentscantakeshortcoursestohelpthemdealwiththeirtensions.Thesecoursesteachstudentshowtorelaxtheirbodies.
Studentsaretrainedtobecomecalminverytensesituations.Bycontrollingtheirnervousness,theycanlettheirmindsworkatease.Learnedinformationthencomesoutwithoutdifficultyonatest.
AnexpertattheUniversityofCaliforniaexplains:"Withalmostallstudents,relaxationandlessstressarefeltaftertakingourprogram.Mostofthemexperiencebettercontrolduringtheirtests.
Almostallhavesomeimprovement.Withsome,theimprovementisverygreat."
To"blankout"isprobably______ A．tobelikeablanket
B．tobesureofananswer
C．tobeunabletothinkclearly
D．toshowknowledgetotheteacher
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答案解析：