-Iamwornoutnow．Istayeduplastnighttofinishthereport．-Oh？You．Theprofessoraskedustohanditinnextweek．（）A.needn'thaveB.wouldn'thaveC.couldn'thaveD.can't
-I am worn out now．I stayed up last night to finish the report．
-Oh？You ______．The professor asked us to hand it in next week．（ ）
A. needn't have
B. wouldn't have
C. couldn't have
D. can't have
本题是两人之间的对话，选项中有语义省略的现象，have后面省略了"stayed up last night to finish the report"．need not have done表示过去已做…事了，但事实上没有必要做．wouldn't have done它表示的是与过去事实相反之假设的结果，意思是"（过去）当时就不会做…了"，而实际上做了…；cannot have done/couldn't have done这两个形式表示推测，意思是"过去应该不可能做…"．根据句子所表达的意思和下文的语境"The professor asked us to hand it in next week．"可知答案选A．
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