Question

I _____ have written to him because he phoned me shortly afterwards.

A. ought to      B. must      C. couldn’t      D. needn’t

Answer 1

D

解析:

needn’t have done“本来不必做”，隐含实际上已经做了，从下文 “此后不久他就给我打了电话”可知用needn’t have written to him。