单选题The supercharger takes air out of the surrounding atmosphere and then feeds it to the engine’s （）.A inlet valvesB exhaust valvesC emergency valvesD run-return valves

According to the passage，what is one disadvantage of skyscrapers that have mirrored walls?

A. The exterior surrounding air is heated。

B. The windows must be cleaned daily.

C. Construction time is increased.

D. Extra air-conditioning equipment is needed.

In Leon Nacson’s view, air and water are our Number One priorities for the following reasons except ().

A、he cannot understand why people are polluting air and water

B、there will definitely be no fresh air and clean water for future generations

C、we would run out of air and water if we didn’t stop polluting them

D、air and water polluting are the current and futu

A、disgusting

B、pleasing

C、wonderful

D、disturbed

Before petroleum______, another way has to be found.

A、takes out

B、runs out

C、makes out

D、works out

A、that

B、what

C、when

D、how

The experiment is carried cut to prove ______.

A. water pushes on your body when you swim underwater.

B. the earth is surrounded by a layer of air called the atmosphere.

C. the pressure of air around us has a powerful force.

D. the air pressure is not equalized around us.

The diamond is a solid and the air is a (fluid).选择能代替括号里的选项

A、gas

B、liquid

C、current

D、atmosphere

A. rate

B. proportion

C. extent

D. amount

The air surrounding us is important to everyone. Without air, we could not （1） Everyone understands that. But air is necessary（2）many other ways that are not always so obvious or widely known. For example, if we did not have air, （3） would be no sound. Sound travels through air. Where there is no air, there is no sound. （4）air, there would be no fire. There would be no automobiles, （5） motors need air in order to operate. Without air there would be no wind or clouds. There would be no （6）, as we know it. The night time would be very（7）, the days very hot. We would be forced to seek shelter from the sun, （8）there would be no atmosphere to protect us from the sun’s deadly rays. The atmosphere is all the air surrounding the （9） . Atmosphere pressure is the weight of all that air against the （10）of the earth. If we did not have atmospheric pressure, we could not have automobile tires. The tires would swell or burst if they did not have the pressure of the atmosphere against their surface.

1、 A. living B. lively C. exist D. alive

2、 A. under B. of C. on D. in

3、 A. there B. they C. it D. we

4、 A. Despite B. With C. As D. Without

5、 A. however B. but C. since D. and

6、 A. air B. weather C. breeze D. climate

7、 A. warm B. cool C. cold D. hot

8、 A. as B. so C. that D. so that

9、 A. floor B. ground C. land D. earth

10、 A. top B. surface C. face D. coverage

Which of the following problems should be taken when cleaning the air filter on a diesel engine equipped with a turbocharger? .

A.Reduce engine speed to idle before removing the filter

B.Soak the dirty filter in kerosene only

C.Blow out the air inlet with compressed air

D.Cover the air inlet after removing the filter