By the time of 1969, there were many space explorations.A、have beenB、must beC、

游客2023-12-31 29

问题 By the time of 1969, there were many space explorations.

选项 A、have been
B、must be
C、had been
D、must have been

答案 C

解析根据时间状语by the time of 1969可判断本句表示过去某时刻前发生的动作或状态，应用过去完成时，因此答案为C。

转载请注明原文地址:http://tihaiku.com/zcyy/3322547.html

相关试题推荐

随机试题

最新回复(0)

Bythetimeof1969,thereweremanyspaceexplorations.A、havebeenB、mustbeC、