Câu hỏi:
13/03/2020 3,158Read 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 34 to 40.
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. For example, sulfur dioxide has detectable health effects at 0.08 parts per million (ppm), which is about 400 times its natural level. Carbon monoxide, however, has a natural level of 0.1 ppm and is not usually a pollutant until its level reaches about 15 ppm.
What does the passage mainly discuss?
Đáp án chính xác
Câu hỏi trong đề:
Tổng hợp đề thi thử THPTQG môn Tiếng Anh có đáp án !!
Sách mới 2k7: Tổng ôn Toán, Lí, Hóa, Văn, Sử, Địa…. kỳ thi tốt nghiệp THPT Quốc gia 2025, đánh giá năng lực (chỉ từ 110k).
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Trả lời:
Giải bởi Vietjack
B
Vấn đề chính được đề cập trong bài là:
A. ảnh hưởng kinh tế của ô nhiễm không khí
B. những thành phần cấu tạo nên một chất gây ô nhiễm không khí
C. Chất thải gây ô nhiễm không khí có tác hại như thế nào
D. ảnh hưởng của hợp chất được thêm vào trong không khí
Dẫn chứng: 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.
Tạm dịch: Một chất gây ô nhiễm không khí được định nghĩa là một hợp chất được con người thêm trực tiếp hoặc gián tiếp vào khí quyển với số lượng như ảnh hưởng đến con người, động vật, thực vật hoặc vật liệu bất lợi.
=> Đáp án B
Nhà sách VIETJACK:
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