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

题目

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

答案

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...