Câu hỏi:
17/03/2020 399Read 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.
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:
Bộ đề thi thử 2019 Tiếng Anh cực hay có lời giải chi tiết !!
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).
Quảng cáo
Trả lời:
Giải bởi Vietjack
Đáp án B.
Nên làm câu này cuối cùng sau khi đã hoàn thành các câu khác để hiểu hơn về bài.
Phân tích: Xét các đáp án:
A. The economic impact of air pollution: Ảnh hưởng kinh tế của ô nhiêm không khí.
B. What constitutes an air pollutant: Những thứ cấu tạo nên ô nhiễm không khí.
C. How much harm air pollutants can cause: ô nhiễm không khí cỏ thể gây ra mức thiệt hại như thế nào.
D. The effects of compounds added to the atmosphere: Ảnh hưởng của hợp chất vào không khí.
|
EXTRA |
|
impact (n): sự ảnh hưởng - effect = influence - have impact on sth/ sb: có ảnh hưởng đến ai, cái gì |
Nhà sách VIETJACK:
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
He was so mean that he could not bear to ___ the smallest sum of money for the charity appeal.
Xem đáp án »
17/03/2020
26,902
Câu 2:
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
Too many factories dispose ___ their waste by pumping it into rivers and the sea.
Xem đáp án »
17/03/2020
23,531
Câu 3:
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
The ___________ polluted atmosphere in some industrial regions is called “smog”.
Xem đáp án »
17/03/2020
22,261
Câu 4:
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
The child who was caught ___________ was made to stand in the comer of the classroom.
Xem đáp án »
17/03/2020
12,524
Câu 5:
Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.
Woman liberated from child care can pursue their own interest.
Xem đáp án »
17/03/2020
12,316
Câu 6:
Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) CLOSEST in meaning to the underlined word(s) in each of the following questions.
Excessive amounts of lead in the air can decrease a child’s intelligence.
Xem đáp án »
17/03/2020
12,094
Câu 7:
Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
Unlike the other Asian states, Singapore has hardly any raw materials, _________
Xem đáp án »
17/03/2020
11,880
về câu hỏi!