If you _____ smoke, please go outside because this is a non-smoking office.
| A．must | B．should | C．can | D．may |
It is said in Australia there is more land than the government knows ________.
| A．it what to do with | B．what to do it with |
| C．what to do with it | D．to do what with it |
I like getting up very early in summer.The morning air is so good ________.
| A．to be breathed | B．to breathe |
| C．breathing | D．being breathed |
—Is Bob still performing?
—I'm afraid not.He is said ________ the stage already as he has become an official.
| A．to have left | B．to leave |
| C．to have been left | D．to be left |
The flu is believed ________ by viruses that like to reproduce in the cell inside the human nose and throat.
| A．causing | B．being caused |
| C．to be caused | D．to have caused |
________ the meeting himself gave them a great deal of encouragement.
| A．The president will attend |
| B．The president to attend |
| C．The president attended |
| D．The president's attending |