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外语
Before the first non-stop flight made in 1949, it ______necessary for all planes to land for refueling.
Before the first non-stop flight made in 1949, it ______necessary for all planes to land for refueling.
admin
2013-04-22
62
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
由before引导的时间状语从句是一般过去时,所以主句应该采用过去完成时。
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专业英语四级
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