Colin was about to get off the camel a child ran towards him.A. whileB. whenC. asD. since

问题补充：

Colin was about to get off the camel a child ran towards him.

A. while

B. when

C. as

D. since

答案：

A. while

(答案→)B. when

C. as

D. since

解析：考查固定结构：be about to do when…刚要做…这时…，句意：Colin刚要下骆驼这时一个男孩朝他跑过来。选B。