On Christmas Eve, we put up some balloons to _______ the festival atmosphere.
| A．make for | B．add to | C．add up | D．join in |
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 |
Staying in a hotel in Shanghai one day costs ____ renting a house in my hometown for a week.
| A．the three times price of | B．three times the price of |
| C．as much as three times | D．as much three times as |
The woman managed to send her three children to universities but ______ came to see her when she was old and seriously ill.
| A．none | B．all | C．neither | D．both |