You are supposed ________ the work yesterday but you forgot.
| A．to finish | B．to be finishing | C．to have finished | D．had finished |
Fred entered without knocking and, very out of breath, sank _________ a chair.
| A．on | B．off |
| C．into | D．to |
The open-air celebration has been put off __________ the bad weather.
| A．in case of | B．in spite of |
| C．instead of | D．because of |
__________ fire, all exits must be kept clear.
| A．In place of | B．Instead of |
| C．In case of | D．In spite of |
Some students often listen to music __________ classes to refresh themselves.
| A．between | B．among |
| C．over | D．during |
— __________ when has the country been open to international trade?
— 1978, I suppose.
| A．Since | B．In |
| C．From | D．After |