All flights ______ because of the storm,they decided to take the train.

问题描述:

All flights ______ because of the storm,they decided to take the train.
a.having cancelled b.were cancelled
c.have been cancelled d.having been cancelled

D本句有主语,they decided to take the train有主语、谓语,成分完整,所以前面只能用从句或者非谓语结构(分词或者动词不定式),但是从句需要有关联词或者连接词引导,不过题目中没有关联词或者连接词,因此不能构成...