Having been attacked by terrorists, .
A. doctors came to their rescue
B. the tall building fell down
C. an emergency measure was taken
D. warnings were given to tourists
网友回答
A. doctors came to their rescue
(答案→)B. the tall building fell down
C. an emergency measure was taken
D. warnings were given to tourists
解析：考查非谓语动词用法。非谓语动词做状语的条件就是它的逻辑主语必须是句子的主语。本题的非谓语动词为Having been attacked，它的逻辑主语是动作的承受者。只有B的主语是攻击的承受者。故B正确。句意：被恐怖分子攻击以后，这栋高楼倒塌了。