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. 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 changes. When the first air pollution laws were established in England in the fourteenth century, ...
Bạch Tuyết | Chat Online | |
03/09 22:57:08 (Tiếng Anh - Lớp 12) |
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.
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 changes. 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 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 more important air pollutants, such as sulfur oxides, carbon monoxides 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 region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an 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.
Which of the following is best supported by the passage?
Lựa chọn một trả lời để xem Đáp án chính xác Báo sai đáp án hoặc câu hỏi |
A. One of the most important steps in preserving natural lands is to better enforce air pollution laws. 0 % | 0 phiếu |
B. Human activities have been effective in reducing air pollution. 0 % | 0 phiếu |
C. To effectively control pollution, local government should regularly review their air pollution laws. 0 % | 0 phiếu |
D. Scientists should be consulted in order to establish uniform limits for all air pollutants. 0 % | 0 phiếu |
Tổng cộng: | 0 trả lời |
Trắc nghiệm liên quan
- Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.‘‘Do you know how to start this computer?’’‘‘_______________________’’. (Tiếng Anh - Lớp 12)
- Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges.‘‘I’m not sure what to do this evening. Any ideas?’’‘‘_______________________’’ (Tiếng Anh - Lớp 12)
- 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. An air pollutant is defined as a compound added directly or indirectly by humans to the atmosphere in ... (Tiếng Anh - Lớp 12)
- Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.The marathon runner ____________ for nearly one hour and a half when she____________ to the pavement (Tiếng Anh - Lớp 12)
- Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.Having been served dinner, ____________ (Tiếng Anh - Lớp 12)
Trắc nghiệm mới nhất
- Khi các bộ phận của bao hoa tuần tự vừa chồng vừa bị chồng lên nhau, có thể cùng chiều hoặc ngược chiều kim đồng hồ, ta có: (Tổng hợp - Đại học)
- Cánh tương đương cánh cờ nằm phía trong, bị hai cánh bên phủ lên, hai cánh này lại bị hại cánh trước phủ lên là: (Tổng hợp - Đại học)
- Khi các bộ phận của bao hoa đặt cạnh nhau mà không phủ lên nhau, ta có: (Tổng hợp - Đại học)
- Hoa đơn tính là hoa: (Tổng hợp - Đại học)
- Hoa lưỡng tính, hoa đực và hoa cái mọc trên cùng một cây riêng biệt thì gọi là: (Tổng hợp - Đại học)
- Cây tạp tính (đa tính) là cây: (Tổng hợp - Đại học)
- Hoa lưỡng tính là: (Tổng hợp - Đại học)
- Hoa lưỡng tính là hoa: (Tổng hợp - Đại học)
- Hoa đực và hoa cái mọc trên hai cây riêng biệt thì gọi là: (Tổng hợp - Đại học)
- Hoa đực và hoa cái mọc trên cùng một cây thì gọi là: (Tổng hợp - Đại học)