问题

You look unhappy, what’s happening, 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

You return the book now. You can keep it until next week if you like.

But for their help，we the program in time.

I think it’s necessary to learn how to work in groups. —I quite agree. Sometimes it’s even than grades.

The fellow left without a word as if________．

You’d better _________ smoking, you’ll be healthier.—Thanks. I’ll try my best.