he would have passed the exam.A. If he were to studyB. If he studied hardC. Had he studi

问题补充：

， he would have passed the exam.

A. If he were to study

B. If he studied hard

C. Had he studied hard

D. Should he study hard

答案：

A. If he were to study

B. If he studied hard

(答案→)C. Had he studied hard

D. Should he study hard

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