Scientists are confident that they can make lasers which can ____ missiles.
| A．knock down | B．knock out | C．knock into | D．knock off |
It’s standard practice for a company like this one______ a security officer.
| A．employed | B．being employed | C．to employ | D．employs |
Sometimes, ________ we show our gratitude for a person is reflected in the kind of food we serve him or her.
| A．when | B．whether | C．why | D．how |
________they decide which college to go to，students should research the admission procedures.
| A．As | B．While | C．Until | D．Once |
—Could I use your car tomorrow morning?
—Sure. I a report at home.
| A．will be writing | B．will have written |
| C．have written | D．have been writing |
He_____ articles for our wall-newspaper these years, and he____ about thirty articles.
| A．has written; wrote | B．has been writing; wrote |
| C．is writing; has been writing | D．has been writing; has written |