Mr.Smithcouldn’topenthedoorbecausehisnaughtyboy

问题详情：

Mr. Smith couldn’t open the door because his naughty boy _______ it from the inside

A. would lock     B. was locking       C. has locked  D. had locked

【回答】

D

知识点：过去完成时及其被动式

题型：选择题