题目内容：
根据以下材料，回答题Astudentwenttocollegeafter 41 allhisschoolexaminations.Thereheputhisnamedownforworldgeography, 42 afterthefirstday,hedidnotgoto 43 anymore.Theteachernoticedthatthisstudentwas 44 absentandthoughtthathehadchangedto 45 class.Hewasvery 46 whenhesawtheboy'snameonthelistofstudents 47 wantedtotakethegeographyexamination 48 theendoftheyear.
Theteacherhadpreparedadifficultexaminationpaper,whichcovered 49 hehadtaught,andhewaseagertosee 50 thisstudentansweredthequestions.Heexpectedthathisanswerwouldbevery 51 ;butwhenheexaminedhispapercarefully,hefoundonlyonesmallmistakeinthem. 52 thissurprisedhimverymuch,hewentthroughthepaper 53 ,butwasstillnotabletofind 54 onemistake,sohesent 55 thestudenttoquestionhimabouthiswork.Whenthestudenthad 56 theroom,theteachersaidtohim,"Iknowthatyoucametomyclassonlyonceonthefirstdayandthatyouhavebeenabsentfromalltheothers.YetIhavefoundonlyonesmallmistakeinyour
paper. 57 isthat?"Oh,I'msorryaboutthatmistake,sir,"answeredthestudent."Aftertheexamination,Irealized 58 Ioughttohavewritten.Iwouldnothavemadethatmistake 59 Ihadnotbeenconfusedbyyour 60 lecture."
A．having
B．taking
C．passing
D．failing
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答案解析：