__________ you understand the rule, you will have no further difficulty.
| A．While | B．Once | C．Though | D．Unless |
The letters WHO _______ the World Health Organization.
| A．repreasented | B．meaning | C．stands for | D．stand for |
The conference has been held to discuss the effects of tourism _____ the wildlife in the area.
| A．on | B．in | C．at | D．with |
In order to make our city green, ____.
| A．it is necessary to have planted more trees | B．our city needs more trees |
| C．we must plant more trees | D．many more trees need to plant |
Tom doesn’t _______ Ted’s plan for the party.
| A．think bad about | B．think good over | C．think highly of | D．think better over |
The films produced by Disney _____ all over the world.
| A．are used to show | B．used to be shown |
| C．are used to be shown | D．used to show |