Question

We have done things we ought not to have done and ________ undone         things we ought to have done.

A．left	B．leave
C．will leave	D．leaving

Answer

A

【解析】

试题分析：句意我们已经做了一些我们不应该做的事情，并且留下了一些该做而未做的事情，句中的we ought not to have done和we ought to have done分别做前面先行词things的定语从句，and连接两个并列的谓语，前面谓语动词为have done，and后谓语动词本该为have left，但因为有and连接，就可以把后半句中重复的have省略掉。

考点：本题重点考查并列结构及省略用法。