Before the first non-stop flight made in 1949, it______ necessary for all planes to land for refueling.

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问题 Before the first non-stop flight made in 1949, it______ necessary for all planes to land for refueling.

选项 A、would be
B、has been
C、had been
D、would have been

答案C

解析 句意:1949年进行直航之前,所有飞机都必须降落加油。本题考查时态的应用。句中由before引导的时间状语从句表示句中的动作是发生在过去(1949年)之过去,那么主句就应该使用过去完成时。所以选项C为正确答案。
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本试题收录于: 英语题库普高专升本分类
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