The boy the first prize, but he was so careless as to make a foolish mistake. A.
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The boy _______ the first prize, but he was so careless as to make a foolish mistake.
A. must have gained B. need have gained
C. could have gained D. shall have gained
试题答案
解析：选C。考查情态动词的用法。句意：这个孩子本可以获得一等奖，但他是如此粗心，以至于犯了一个愚蠢的错误。could have done本可以……，表示与过去的事实相反。