问题

Having checked the doors were closed and ______ all the lights were off, the boy opened the door to his bedroom

A:why
B:that
C:when
D:where

正确答案是：

同类题型

Have you had a holiday recently— _____ .

People are puzzled _____ they read the book.

the terrorist attack that happened in Kunming on March 1, the spokesman said that all suspects responsible for it would be severely punished.

I don’t like talking on telephone；I prefer writingletter

_____ some mammals came to live in the sea is not known[ ]