All flightsbecause of the storm they had to wait in the hall.A. have put offB. were put o

问题补充：

All flightsbecause of the storm, they had to wait in the hall.

A. have put off

B. were put off

C. have been put off

D. having been put off

答案：

A. have put off

B. were put off

C. have been put off

(答案→)D. having been put off

解析：考察独立主格。根据句子结构可知，该句主句的主语是they，分词部分主语是all flights，因此是独立主格结构，独立主格结构是n + 分词形式 构成，即D

句意为，所有的航班已经被取消，因为暴风雨，他们不得不在大厅里等。