Scientists say it may be five or six years _______ it is possible to test this medicine on human patients.
| A．since | B．after |
| C．before | D．when |
Sit down, Emma. You will only make yourself more tired, __________ on your feet.
| A．to keep |
| B．keeping |
| C．having kept |
| D．to have kept |
Go back home now, Mary. Your parents __________your safety.
| A．are concerned about |
| B．are concerned with |
| C．are concerned in |
| D．concern of |
I did a lot of work on that book. It annoys me that the editor never __________ that.
| A．refused |
| B．acquainted |
| C．acknowledged |
| D．accused |
The form is said to require __________ in black ink.
| A．filling in |
| B．to be filled |
| C．filling |
| D．to fill in |
To keep healthy ,Mr. Lin __________ climbing as a regular form of exercise after he retired .
| A．took up |
| B．took on |
| C．made up |
| D．made in |