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】此句是occur to sb(想到; 想起)的典型句式，是学习occur单词的一个重点方面。that这里是做主语从句的连接词。