The researchers have discovered __________they believe to be a new species.
| A．which | B．who | C．where | D．what |
_____________ on the portrait, mother was deep in thought.
| A．Fixed her eyes | B．Her eyes are fixed |
| C．Her eyes fixing | D．With her eyes fixed |
An average of 130000 Chinese _________ abroad for studies every year over the past few years, boosting exchanges in the educational fields
| A．was going | B．have been going |
| C．has been going | D．are going |
---- I can’t get through to the general manager’s office anyhow.
---- The line is busy. Someone ___________ the telephone.
| A．can have used | B．can use |
| C．must have used | D．must be using |
As we all know,________, the pollution will get worse and worse.
| A．not if carefully dealt with |
| B．until not carefully dealt with |
| C．if not carefully dealt with |
| D．when not carefully dealt with |
There was a fierce debate about _____we should go on with experiments on creating new life.
| A．which | B．whether | C．that | D．What |