It is believed that a new kind of drug ______ by the scientists and they are hopeful that they will succeed in a few months.
We ______ to clean the blackboard every day.
The old man is ______ under the tree and ______ a paper.
-Can you stand ______ in that way? - Absolutely not.
Don't forget ______ the light when you leave the office.
You'd better not ______ your coat, or you'll get cold.