问题

How long do you think it will be __________ China sends a manned spaceship to the moon— Perhaps two or three years.

A:when
B:until
C:that
D:before;

正确答案是：

同类题型

The river marks the _______ between Mexico and the USA．

How do you go to work—I usually go to work _____.

Have you been to the Great Wall?– Perhaps not in my memory. _______, it might have been during my early childhood.

Luckily, the people there did ______ help him.

Do the Smiths live next to you –No, but they____.