John'sscoreonthetestisthehighestinhisclass,he______veryhard.
A.musthavestudied
B.shouldhavestudied
C.muststudy
D.shouldstudy
正确答案:A本题考查虚拟语气的用法。根据题意:John的考试成绩是最高的,故他肯定考试前努力了。must+have+过去分词,表示对过去的某事作出肯定语气的推测。故选A。

John'sscoreonthetestisthehighestinhisclass,he______veryhard.
A.musthavestudied
B.shouldhavestudied
C.muststudy
D.shouldstudy
正确答案:A