Pollution is a serious problem. Scientists have _______ some good ways to save it.
| A．come up with | B．come on | C．come out | D．come up |
–Who ate my ice-cream?
–It by Eddie.
| A．is eaten | B．was eaten |
| C．was eaten | D．has been eatten |
There used a tree in front of the house, but now it is cut down.
| A．be | B．have |
| C．to be | D．to have |
I the camera for a week already.
| A．bought | B．have bought | C．buy | D．have kept |
You have never visited the place before, you?
| A．did | B．didn’t |
| C．have | D．haven’t |
–Where are the children? – Theyto Beijing.
| A．have been | B．have gone |
| C．have left | D．have arrived |