Having been attacked by terrorists, .
A. doctors came to their rescue
B. the tall building collapsed
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 collapsed
C. an emergency measure was taken
D. warnings were given to tourists
解析：考查非谓语动词。非谓语动词要和主句共用一个主语。只有B的主语能被分词 使用。根据句意其它都不合适。句意：这座大楼被恐怖分子袭击后就倒塌了。根据句意说明B正确。