.
No teachers are permitted ________ in the classroom or in the office.
| A．smoke | B．smoking | C．to smoke | D．smoked |
This course of study________to help those________to go abroad is popular with young people.
| A．designing；wishing | B．designed；wished |
| C．designing；wished | D．designed；wishing |
The flu is believed________by viruses that like to reproduce in the cells inside the human nose and throat.
| A．causing | B．being caused |
| C．to be caused | D．to have caused |
He hadn’t paid for his water so the company had________it off.
| A．put | B．keep |
| C．shut | D．take |
In the last few years thousands of films________all over the world.
| A．have produced | B．have been produced |
| C．are producing | D．are being produced |
The manager thought________difficult to finish the task in such a short time.
| A．that | B．it |
| C．this | D．him |