Mr.Smithcouldn’topenthedoorbecausehisnaughtyboy

問題詳情：

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

知識點：過去完成時及其被動式

題型：選擇題