Answer:
have fallen by more than one-half.
Explanation:
Thick, noticeable smog in many of the cities and manufacturing centers of the United States helped bring the 1970 e Clean Air Act to spur passage at the height of the national environmental movement. The ensuing modifications were intended to enhance its effectiveness and address newly recognized problems of air pollution such as acid rain and stratospheric ozone layer damage. The Clean Air Act allows EPA to set national environmental air quality levels for certain specific and prevalent contaminants, based on the latest research, to protect public health and welfare nationally. Certain main regulations are intended to reduce the rise in emissions from increasing motor vehicle numbers and new manufacturing plants.
Britain and Spain were in the revolution.
Athens was ruled by a king
The U.S. tried to stop communism from spreading globally.
It never really failed but he did create a period which some refer to as the imperial presidency due to his desire to rule like a king. It pretty much was the first time that a president was using all of his powers listed in the constitution. Hope this helps:)
