单选题
John’s score on the test is the highest in the class; he _____ last night.
Amust study
Bshould have studieD
Cmust have studieD
Dis sure to study
正确答案
答案解析
本题考查情态动词 C选项，句意：约翰的考试分数全班最高;他昨天晚上一定学习了。表示对过去某一动作行为的猜测须要用must have done这一句型结构。 A，选项，对现在的猜测，与题意不符，故排除。 B，选项，本该做而未做，故排除。 D，与题意不符，故排除。 故正确答案为C选项。