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。