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Câu hỏi:

21/07/2024 324

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 30 to 34.

An air pollutant is defined as a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals, vegetation, or materials adversely. Air pollution requires a very flexible definition that permits continuous change. When the first air pollution laws were established in England in the fourteenth century, air pollutants were limited to compounds that could be seen or smelled - a far cry from the extensive list of harmful substances known today. As technology has developed and knowledge of the health aspects of various chemicals has increased, the list of air pollutants has lengthened. In the future, even water vapor might be considered an air pollutant under certain conditions.

Many of the more important air pollutants, such as sulfur oxides, carbon monoxide, and nitrogen oxides, are found in nature. As the Earth developed, the concentration of these pollutants was altered by various chemical reactions; they became components in biogeochemical cycles. These serve as an air purification scheme by allowing the compounds to move from the air to the water or soil. On a global basis, nature's output of these compounds dwarfs that resulting from human activities.

However, human production usually occurs in a localized area, such as a city. In such a region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an increased concentration of noxious chemicals in the air. The concentrations at which the adverse effects appear will be greater than the concentrations that the pollutants would have in the absence of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact, the numerical value tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area.

What does the passage mainly discuss?

A. The economic impact of air pollution.

B. What constitutes an air pollutant. 

Đáp án chính xác

C. How much harm air pollutants can cause. 

D. The effects of compounds added to the atmosphere.

Trả lời:

verified Giải bởi Vietjack

Chọn B.

Đáp án là B.

Giải thích: Bài văn chủ yếu bàn về :

A. Tác động về mặt kinh tế của ô nhiễm không khí

B. Những gì hợp thành 1 tác nhân ô nhiễm không khí

C. Mức độ nguy hại mà chất ô nhiễm gây ra

D. Ảnh hưởng của các hợp chất bị thêm vào không khí

Câu trả lời này có hữu ích không?

0

CÂU HỎI HOT CÙNG CHỦ ĐỀ

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Câu 2:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 35 to 42.

The Nobel Peace Prize is awarded annually and the first woman to win this prize was Baroness Bertha Felicie Sophie von Suttner in 1905. In fact, her work inspired creation of the Prize. The first American woman to win the prize was Jane Addams, in 1931. However, Addams is best known as the founder of Hull House.

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Before World War I, Addams was probably the most beloved woman in America. In a newspaper poll that asked, “Who among our contemporaries are of the most value to the community?” Jane Addams was rated second, after Thomas Edison. When she opposed America’s involvement in World War I, however, newspaper editors called her a traitor and a fool, but she never changed her mind. Jane Addams was a strong champion of several other causes. Until 1920, American women could not vote. Addams joined in the movement for women’s suffrage and was a 7 vice president of the National American Woman Suffrage Association. She was a founding member of the National Association for the Advancement of Colored People (NAACP), and was president of the Women’s International League for Peace and Freedom. Her reputation was gradually restored during the last years of her life. She died of cancer in 1935.

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Câu 3:

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Câu 5:

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________, tell him I have gone to London.

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Câu 6:

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

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Câu 7:

 

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Câu 8:

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

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Câu 9:

 

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Câu 13:

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Câu 14:

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Câu 15:

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