Reportedly yesterday a group of American soldiers were walking along the road in Irap when

问题补充：

Reportedly yesterday a group of American soldiers were walking along the road in Irap when a bomb was .

A. set out

B. set about

C. set off

D. set up

答案：

A. set out

B. set about

(答案→)C. set off

D. set up

解析：短语辨析。A动身，出发；B开始做…;C 开始，引爆；D设立，建立；句意：据报道，昨天一群美国士兵正在伊拉克巡逻，在这时一颗炸弹被引爆了。根据句意说明set off在本句中指引爆，故C正确。