---Be careful. You might fall into the river.
---Thank you. I ________ I ________ so close to it．
| A．didn’t know; am standing |
| B．don’t know; am standing |
| C．didn’t know; was standing |
| D．didn’t know; would standing |
Stop smoking, ________ your health will get worse soon.
| A．and | B．or | C．but | D．s o |
________ dog is ________ useful animal and ________ honest friend as well.
| A．A; a; an | B．A; an; a | C．The; an; a | D．The; an; an |
The garbage too much space .
A. takes away B.takes off C. takes up
We should do everything we can the environment .
A. to protect B. protectC. protecting
______of the earth ______ covered by water.
A. Two thirds; is B. Two thirds; are C. One thirds; is