一During the APEC summit（峰会)，Beijing’s sky was so blue and clear.
－It APEC blue.But too bad it no longer stays that way．
| A．is called | B．are called | C．called | D．calls |
Peter, you should leave the light when you’re out.
| A．off | B．closed | C．on | D．open |
I think it’s unusual thing to find a UFO.
| A．a | B．an | C．the | D．不填 |
The young lady________ is talking with our teacher comes from America.
| A．who | B．whom | C．which | D．whose |
Waste paper mustn’t _______. We should keep our environment clean.
| A．throw away | B．thrown away |
| C．be thrown away | D．been thrown away |
Come on! You will catch up with others _______ you work hard.
| A．if | B．unless |
| C．although | D．so |