Question

by 1980 the bridge_____ A was completed B had been completed

C has been completed 请问该选哪一个？为什么？求高人解答

Answer 1

选C。有by+某时刻的一般都要用完成时。如果该时刻已过去，就用过去完成时，如本题选C。
如果该时刻是未来的，应用将来完成时。如By the end of next year, we'll have learnt 10,000 words.如果该时刻是现在，就用现在完成时。如He should have arrived by now.

追问

可题上明明是过去的时间啊

Answer 2

B by +过去时间，时态选择过去完成时态。
祝学习进步！

追问

complete可延续吗

追答

非延续性动词。

追问

那为什么不选a呢

Answer 3

B
by + 过去时间------用“过去完成时”。

Answer 4

B。在1980年之前已经被完成的

Answer 5

A was completed