Question

【题目】It's impolite to keep someone________ for a long time.

A.waitB.to waitC.waitingD.have waited

Answer 1

【答案】C

【解析】

句意：让人久等是不礼貌的。

考查固定用法，A. wait 动词原形；B. to wait动词不定式；C. waiting动词现在分词；D. have waited现在完成时。根据“keep sb doing sth让某人一直做某事”，故选C。