Question

【题目】It suddenly occurred to him ________ he had left his keys in the office.

A. whether B. where

C. which D. that

Answer 1

【答案】D

【解析】D

解析　It occurs/occurred to sb. that...某人想到/想起。it是形式主语，主语从句成分完整，不能用连接代词which引导，whether与where不符合句意。故选D项。