问题

You look unhappy, my son?— I’m wondering how long it’ll be we come to China again[ ]

A: since
B: when
C: before
D: after

正确答案是：

同类题型

Nobody can achieve anything of realsignificance _____ he works very hard

Today the forests are getting fewer and fewer. We must______ down too many trees.

What do you know about Darwin after he returned from the trip by sea?— Well, he got married and ________ down to live in London. [ ]

My parents didn’t know ____ dinner with them next Sunday.

Is this a photo _____ your family