I was just about to go to bed last night the telephone rang.A. whileB. whenC. asD. before

问题补充：

I was just about to go to bed last night the telephone rang.

A. while

B. when

C. as

D. before

答案：

A. while

(答案→)B. when

C. as

D. before

解析：句意：昨晚，我正要去上床睡觉时，突然电话铃响了。be about to do sth when…正要做某事的时候，突然。固定句型，故选B