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Why was 1990 an important year regarding air quality? Select two options.

1.The United States took first steps to keep the air clean.
2. Cost-effective ways to reduce pollution were emphasized.
3.The United States created the environmental protection agency.
4.Modifications and improvements were made to the Clean Air Act.
5.Funding was established under the Clean Air Act to study air pollution.

Imagine a rocket launching from earth and travelling to the moon. in which order would the rocket pass through the layers of the atmosphere? thermosphere, mesosphere, stratosphere, troposphere troposphere, mesosphere, stratosphere, troposphere thermosphere, stratosphere, mesosphere, troposphere troposphere, stratosphere, mesosphere, thermosphere

When coal has reached it hardest, darkest form, it is called select one: 0 a. sub-bituminous b. lignite c. bituminous d. antrhacite next page

Astudent reads the following text in a science book: scientific evidence tells us that the cause of earths four seasons is the tilt of earth as it revolves around the sound the student is instructed to illustrate this information in a science book. how will the student illustrate winter in the northern hemisphere? a.earths northern hemisphere will tilt away from the sun. b. earths northern hemisphere will tilt toward the sun. c.earths orbit will be farther away than from the sun d. earths southern hemisphere will tilt away from the sun.