30. The No. 5 subway line, ______in October, 2007, has greatly improved the traffic conditions in Beijing.
| A．opened | B．was opened | C．being opened | D．to be opened |
With all the work on hand, I ______to the cinema last night. How I regret it!
| A．shouldn’t have gone | B．might have gone |
| C．can’t have gone | D．must have gone |
The two researchers originally set out to study the zebras in Africa and discovered a new species of tiger ______.
| A．by chance | B．in addition |
| C．by nature | D．in need |
The police warned that anyone ______guilty of taking drugs in that country would be put in prison.
| A．to find | B．found |
| C．finding | D．having found |
–Have you listened to ______ weather forecast, Linda?
–Yes. It says that there will be ______ heavy rain this weekend.
| A．the; the | B．a; the |
| C．the; a | D．a; a |
–Is it all right if I sit here?
–______, sir. The seats are for elderly people only.
| A．Better not | B．Go ahead |
| C．As you please | D．No way |