题目内容
All flights______ because of the air traffic control, the passengers had to wait in the hall.
A. were put off B. having put off
C. having been put off D. have been put off
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题目内容
All flights______ because of the air traffic control, the passengers had to wait in the hall.
A. were put off B. having put off
C. having been put off D. have been put off