we were busy ____the classroom when mr wang came in 1.with clean _其他解答

we were busy ____the classroom when mr wang came in 1.with clean 2.cleaning 3.to clean 4.for

人气：459 ℃　时间：2020-03-27 01:22:56

解答

选项应该是2,
词组结构为 be busy doing sth,忙于做某事,这是一个基础结构,也属于习惯用法