Reportedly, yesterday a group of American soldiers were walking along the road in Iraq when a bomb was _______, three of whom were killed．
A.set offB.set outC.set upD.set about在线课程A
试题分析：考查词组;A. set off引发，引爆，出发，B. set out开始，动身，C. set up建立，D. set about出发，句意是：据报道，昨天一群美国士兵沿着伊拉克的公路走，这时炸弹爆发了，有三人丧生。选A。
考点：考查动词短语
点评：本题考查了由动词set加不同的副词，介词构成的短语，要注意一词多义的现象。在结合上下选择适当的选项。