Question

Last night Li Ping watched the football match at home when he ______ his homework.

1. A.
   need have done
2. B.
   must haven done
3. C.
   should have done
4. D.
   could have worked

Answer 1

C
考察虚拟语气。句意：当他应该写作业的时候，昨晚丽萍在家看足球比赛了。“should+have+done”意思是“本来应该做某事，而实际没做。”故选C。