单选题
We have done things we ought not to have done and ______ undone things we ought to have done.
【正确答案】
C
【答案解析】[解析] leave后面可以跟带现在分词、过去分词、不定式、形容词、介词短语的复合结构及其他成分。如：Don"t leave her waiting. It"s better to leave. I"ll leave you to settle the business. His illness has left him weak. I"ll leave it to you to buy the tickets/leave buying the tickets to you.本题的leave后面跟的是带过去分词的复合结构，因为宾语太长(后面有定语)，所以将过去分词undone提到宾语things的前面了。