I was about to get on the bus someone called me from behind.A. untilB. whetherC. whileD. w

问题补充：

I was about to get on the bus someone called me from behind.

A. until

B. whether

C. while

D. when

答案：

A. until

B. whether

C. while

(答案→)D. when

解析：考查连词。此题是一个固定句型：be about to do … when ,即将做某事，正在那时，句意：我刚要上车正在这时有人在后面叫我。故选D。