______ environmental damage is done，it takes many years for the ecosystem to recover．
| A．Even if | B．If only |
| C．As if | D．Once |
After Yang Liwei succeeded in circling the earth ,_______our astronauts desire to do is walk in space .
| A．where | B．what | C．that | D．How |
we can not figure out ____quit a number of insects ,birds ,and animals are dying out .
| A．that | B．as | C．why | D．when |
He was chosen _________ of the company.
| A．manager | B．a manager | C．the manager | D．as a manager |
In the botanic garden we can find a（n）______of plants that range from tall trees to small flowers.
A．spec ies |
B．group | C．amount | D．variety |
The experiment turned out to be ________, which wasn’t ______ they wanted.
| A．a completely failing; as | B．a complete failure; what |
| C．completely failure; that | D．failed; 不填 |