Cùng tham khảo Đề KS chuyên đề lần 1 môn tiếng Anh lớp 12 năm 2018-2019 - THPT Tam Dương - Mã đề 485 sau đây để biết được cấu trúc đề thi cũng như những dạng bài chính được đưa ra trong đề thi. Từ đó, giúp các bạn học sinh có kế hoạch học tập và ôn thi hiệu quả. | SỞ GD & ĐT VĨNH PHÚC TRƯỜNG THPT TAM DƯƠNG ĐỀ KHẢO SÁT CHUYÊN ĐỀ LẦN 1 MÔN: TIẾNG ANH 12 Thời gian làm bài: 60phút; (50 câu trắc nghiệm) Mã đề thi 485 (Học sinh không được sử dụng tài liệu) Họ, tên học sinh:.SBD: . 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 1 to 8. 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 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
