真题练习
765.Maybe if I _______ science,and not literature then,I would be able to give you more help.

A.studied
B.would study
C.had studied
D.was studying

766.I _____ sooner but I didn't know that they were waiting for me.

A.had come
B.was coming
C.would come
D.would have come

答案解析

765.答案是C;考查虚拟语气用法；then表示过去的时间，if引导的从句是对过去的虚拟，故用过去完成时。
766.答案是D;but I don't know表示过去的真实情况，可以断定主句是对过去的虚拟，故用should/would/could/might+have done表示。