We had fun ________ the robots do many different kinds of things.
| A．to watch | B．watched | C．watching | D．watches |
The boss makes the workers ________ long hours every day.
| A．work | B．to work | C．works | D．working |
—________ will you come back from your work, Dad?
—In about half an hour, dear.
| A．How long | B．How often |
| C．What time | D．How soon |
There _______an important meeting this afternoon. All of you should attend it.
| A．will have | B．will be | C．will hold | D．has |
There are three ________ students in their school.
| A．thousands of | B．thousand of |
| C．thousands | D．thousand |