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

I am pretty certain that the latest events you havejust described can only _________ her unhappiness.

fire, all exits(出口) must be kept clean.[ ]

Not many of us really get to see the hard work that happens ______ the scenes to make our favorite movies come to life.

下列句子中，加点成语使用正确的一项是

Every day ____ a proverb aloud several times until you have it memorized.