She is an excellent student in our class, and she always herself in her studies.
| A．hides | B．buries | C．covers | D．leaves |
We can’t figure out ______ quite a number of insects and birds are dying out．
| A．that | B．as | C．why | D．when |
______ environmental damage is done，it takes many years for the ecosystem to recover．
| A．Even if | B．If only |
| C．As if | D．Once |
If Susan ______ for ten more minutes at the party last night, she might have met Johnny Depp, the famous Hollywood star．
| A．stayed | B．would stay |
| C．had stayed | D．would have stayed |
Passers-by rescued a motorcycle driver ______ under a burning car．
| A．was trapped | B．trapping |
| C．having trapped | D．trapped |
More people are choosing to work ______ retirement age．
| A．at | B．in |
| C．for | D．beyond |