Before the first non-stop flight made in 1949, it ______ necessary for all plane

游客2023-09-28 44

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

转载请注明原文地址:http://tihaiku.com/zcyy/3054226.html

相关试题推荐

随机试题

最新回复(0)

[originaltext]M:Willthisflightleaveontime?[/originaltext][audioFiles]202