I was on the point of going to bed Mr. Zhang rang me up.A. asB. whenC. whileD. and

问题补充：

I was on the point of going to bed Mr. Zhang rang me up.

A. as

B. when

C. while

D. and

答案：

A. as

B. when

C. while

D. and

解析：题意：我刚要上床睡觉张先生打来了电话。句中的并列连词when = just at that time, 意为“这时(突然)”。