I was on the highway when this car went past followed by a police car. They ______ at least 150 kilometers an hour.
| A．should have been doing | B．must have been doing |
| C．could have done | D．would have done |
In the past few years, so many areas throughout the world have been hit by such destructive earthquakes, snowstorms and tsunamis ________ we have never experienced before, ________ makes us worried a lot about nature disasters.
| A．that; that | B．as; which | C．which; it | D．when; as |
I don’t think it is __________taking the trouble to explain the question to him.
| A．worth | B．worthy | C．worth of | D．worthwhile |
With trees and grass__________39.6% of the urban area，the city has taken on a new look.
| A．covering | B．covered | C．to be covered | D．being covered |
The elderly _________ good care of in public places like supermarkets and airports; they are likely to get lost.
| A．can have been taken | B．ought to be taking | C．must be taken | D．should take |
Susan, _______ university student from Europe, teaches me _________ art in her spare time.
| A．an; / | B．a; the | C．an; the | D．a; / |