1 . Lisa, I didn't __________(认出)you—you've had your hair cut!

2 . Gun control is a subject________ Americans have argued for a long time.

A．of which

B．with which

C．into which

D．about which

3 . —Coach, can I continue with the training?
—Sorry, you can’t ________you haven’t recovered from the knee injury.

A．until

B．before

C．as

D．unless

4 . His writing is so confusing that it’s difficult to make out ________ it is he is trying to express.

A．that

B．how

C．who

D．what

5 . I have reached a point in my career ________ I need to decide which way to go.

A．that

B．where

C．which

D．why

7 . At the Chinese art festival, there are different stands ________ artists demonstrate their skills and teach the visitors.

A．where

B．which

C．that

D．when

8 . What puzzles Lily's friends is ________ she always has so many crazy ideas.

A．whether

B．why

C．what

D．when

9 . William Hastie once suggested that history informs us of past mistakes ________ we can learn without repeating them.

A．from which

B．in which

C．with whom

D．for whom

10 . We all need to get involved in saving energy ________ it's at work, at home, or at school.

A．unless

B．once

C．whether

D．because