A: Little is known about defining a substance as an air pollutant.
B: The substance isn’t an air pollutant when there is a very little in the air.
C: The substance can’t be judged to be an air pollutant only from its actual concentration level.
D: The actual concentration level means little to peopl
举一反三
- The water (or snow) can become acidified when a pollutant combines with______ in the air.
- What is the talk mainly about A: The definition of air pollutant. B: The causes of air pollution. C: The dangers of air pollutants. D: Ways to fight air pollution.
- There is little air on ______ moon. A: [A] the B: a C: /
- 智慧职教: 3.S1:Isn't the emergency air compressor started? S2:Yes. But the emergency air compressor can't supply enough starting air to the air receiver for the auxiliary engine. Q:How is the emergency air compressor?
- The doctor said that there was only a slim hope of survival for the people in the air crash. A: numerous B: considerable C: moderate D: very little
内容
- 0
M: The air conditioner in my room is broken and I can’t work.W: Why not go to the office What does the woman mean（） A: The man can sleep in the office. B: She can have someone to repair the air conditioner. C: She can work without air conditioner. D: The man can do his work in the office.
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词汇与结构 This relationship between temperature, altitude, and air density can be expressed as a _______ altitude, or the altitude in the International Standard Atmosphere at which the air density would be equal to the actual air density.
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When considering air: 1 - Air has mass 2 - Air is not compressible 3 - Air is able to flow or change its shape when subject to even small pressures 4 - The viscosity of air is very high 5 - Moving air has kinetic energy The correct combination of all true statements is: A: 1, 2, 3 and 5 B: 2, 3 and 4 C: 1 and 4 D: 1, 3, and 5
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Air pollution is becoming worse. As is known to all, air to us is ________ water to fish. No one can imagine how human being can live without air.
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Little progress can be made in the present economic ________ in this underdeveloped country. A: mood B: air C: climate D: fashion