[单项选择]The atmosphere is consisted of certain gases mixed together in definite proportions.（　）.
A. The atmosphere
B. is consisted
C. mixed together
D. in

[单项选择]The atmosphere ______ of certain gases mixed together in definite proportions.
A. composes
B. comprises
C. consists
D. constitutes

[单项选择](The atmosphere) (is consisted) of certain gases (mixed together) (in) definite proportions.（）
A. The atmosphere
B. is consisted
C. mixed together
D. in

[单项选择]The atmosphere,a narrow band of gases surrounding the Earth,is maintained by gravitational pull.


A. clear
B. freezing
C. thin
D. poisonous

[单项选择]Certain layers of the atmosphere have special names __
A. which indicated their character properties
B. whose characteristic properties are indicating
C. what characterize their indicated properties
D. that indicate their characteristic properties

[单项选择]"Greenhouse gases" in Par


A. A．2 refer to ______. oxygenB. hydrogenC. carbon dioxideD. air

[单项选择]They took （　） measures to prevent poisonous gases from escaping.
A. fruitful
B. beneficial
C. valuable
D. effective

[简答题]Plastic 的制作Disadvantage: it will produce gases In some cases, burning it could release toxic fumes.Also, the manufacturing of plastics often created large quantities of chemical pollutants.

[单项选择]Gases differ from solid in that the former have greater compressibility than the latter.


A. 气体与固体的区别在于前者比后者有更大的压缩性。
B. 气体与固体是有区别的，前者比后者有更大的压缩性。
C. 气体与固体是有区别的，前者比后者更能压缩。
D. 气体与固体在压缩性上是没有区别的。

[单项选择] How Global Warming Works Gases in the Earth’’s atmosphere act like glass in a greenhouse-trapping heat and making life on Earth possible. But there is a delicate balance. Burning coal, oil and natural gas increases atmospheric concentrations of these gases. Over the past century, increases in industry, transportation, and electricity production have increased gas concentrations in the atmosphere faster than natural processes can remove them leading to human-caused warming of the globe. The Sources Of Global Warming The major source of global warming is carbon dioxide pollution from power plants, auto mobiles, and industry. Another source is global deforestation. ●Power plants are responsible for more than a third of U. S. CO2 emissions, yet there are no caps on CO2 emissions from power plants or any other industry. ●Gas guzzling cars and light trucks are also responsible for a third of U.S. CO2 emissions. Current regulations allow fo
A. Y
B. N
C. NG