30.The problem lies in ______ the mist may become a thick fog , making the situation even worse.
| A．that | B．which | C．what | D．that whether |
It is in the hall behind the teaching building _____ we usually have our PE lessons on rainy days.
| A．where |
| B．that |
| C．which |
| D．what |
We _____ on this project for four hours. Let’s have a rest.
| A．are working |
| B．have been working |
| C．worked |
| D．had worked |
There are over 58,000 rocky objects in _____ space, about 900 of which could fall down onto _____ earth.
| A．the; the |
| B．/; the |
| C．the; / |
| D．a; the |
—Did you catch what I said?
—Sorry. I _____ a text message just now.
| A．had answering |
| B．have answered |
| C．would answer |
| D．was answering |
I feel so excited! At this time tomorrow morning I _____ to Shanghai.
| A．will be flying |
| B．will fly |
| C．have been flying |
| D．have flown |