A-A+

By the time of 1969 there were many space exp

2022-08-01 20:27:31 问答库阅读 166 次

问题详情

By the time of 1969, there were many space explorations.
A．have been
B．must be
C．had been
D．must have been请帮忙给出正确答案和分析，谢谢！

正确答案：C
解析：时态应用根据时间状语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。