If Harry did not attend the conference last night, he too much work to do．A.had
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If Harry did not attend the conference last night, he ________ too much work to do．
A.had to have had
B.had had
C.must have had
D.must have
试题答案
C
注意条件句中的时态是did not attend，所以判断这不是叙述过去情况的虚拟语气。空格处是对过去情况的猜测——他一定昨天晚上有很多工作要做，所以才没有去参加会议的。