问题

You promised your friend a letter; you ought to ______ days ago.

A:write
B:be writing
C:have written
D:be written

正确答案是：

同类题型

The young man suddenly returned __ a rainy night

Only after spending several nights working on the math problem to wonder whether the problem was wrongly set.

We have different pies, _________ apple pies, cherry pies and strawberry pies.

________ he made up his mind to take a trip to Europe?

Excuse me, could you tell me _______— There’s an e-shop on the third floor. You can make it there.