第19题: [单项选择]All flights _________because of the heavy fog, we had to decide to take the train. A. were canceled B. having canceled C. having been canceled D. have been canceled 参考答案:C 答案解析:所有的航班都因大雾而取消了,所以我们不得不决定乘火车。本题考查分词短语作状语的用法,cancel作vt与主语all flights构成了动宾关系,故用被动语态,取消航班应发生在做决定之前,故用完成时态