—I started off to walk, but Peter gave me a lift.
—Therefore, you ________ after all.
| A．didn’t need walk | B．needed not walk |
| C．need not to walk | D．didn’t need to walk |
Worldwide markets get tighter and the pain only lasts longer ______ international cooperation is strengthened in no time.
| A．because | B．if | C．unless | D．when |
The situation in Haiti after the earthquake was all in a mess, ______ the increasing number of robbery cases.
| A．causing | B．having caused | C．caused | D．to cause |
Measures must be taken before there is another collapse of the coal mine, ______?
| A．must they | B．mustn’t they | C．is there | D．isn’t there |
Look at the naughty boy! You ______ have taught him how to behave himself.
| A．must | B．may | C．can | D．should |
Once harm ______ to the environment, it takes years to have the system recovered.
| A．does | B．is done | C．will be done | D．be done |