---Look! _________ clean the classroom looks !
---Yes. I’m sure somebody __________ it up.
| A．What , has cleaned |
| B．How , cleaned |
| C．What , cleaned |
| D．How ,has cleaned |
Wars are disasters. A large number of people will lose their homes if a war .
| A．breaks out | B．breaks down |
| C．breaks up | D．breaks off |
---How do you like the story?---Interesting,_______ the end of it is not perfect.
| A．though | B．so |
| C．or | D．because |
You are working too hard. You’d better keep a__________ between work and relaxation.
| A．promise | B．secret |
| C．balance | D．diary |
Some people won’t realize the value of their health ________they lose it.
| A．after | B．until |
| C．as | D．when |