Answer: Nitrogen oxides are present in combustion and industrial processes.
Explanation: We are talking about the combustion of coal, oil and gasoline by the emission of vehicles such as ships, airplanes trucks and automobiles, which is specially significant in big cities where there is more traffic . For the industry part there are the electric power plants and large industrial operation plants.
It's purpose was to let people get good places in the government if they passed, but the only people that could take it were people that were already recommended into the government, so the rich and influential continued to run the government and the test was based on Confucianism.
The second oldest American college is Harvard.