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 55 to 64
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
According to the passage, the numerical value of the concentration level of a substance is only useful if _______.
A. it is in a localized area
B. it can be calculated quickly
C. the natural level is also known
D. the other substances in the area are known
Giải bởi qa.haylamdo.com
Đáp án là C
Dựa vào câu 4 đoạn 4 “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” trên thực tế, chỉ số chỉ có ý nghĩa cho tới khi chúng ta nhận ra sự gia tăng tiêu biểu quá nồng độ tự nhiên.
Mark the letter A, B, C or D on your answer sheet to indicate the word or phrase that is OPPOSITE in meaning to the underlined part in each of the following questions.
Humans depend on species diversity to provide food, clean air and water, and fertile soil for agriculture.
Choose the best answer:
While __________ to help Tom with his math, I got impatient because he wouldn‟t pay attention to what I was saying.
Choose the best answer:
Up to the present, George __________ good work in his class.
Choose the best answer:
Because the first pair of pants did not fit properly, he asked for _____
Choose the best answer:
My neighbor is driving me mad! It seems that _____ it is at night, _____ he plays his music!
Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction (from 30 to 34)
Catherine is studying (A) law (B) at the university, (C) and so does (D) John.
Choose the best answer:
I couldn't use the pay phone __________I didn't have any coins with me.
Choose the best answer:
_____________ so many people been out of work as today.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word for each of the blanks from 35 to 44.
WHY I DISLIKE COMPUTERS
Almost everyone says that computers are wonderful and that they are (35) ______ our lives for the better by making everything faster and more reliable, but I am not so sure that this is the (36) ________
The other day I was standing in a large department store waiting to pay for a couple of films for my camera (37) _______ the assistant announced that the computer which controlled the till (38) _______ working. I did not think this was a big problem and I (39)________ to find another counter, but of course, all the machines are part of the same system. So there we were: a shop full of customers, money at the ready, waiting to (40) _______ our purchases, but it was quite clear that none of the assistants knew what to do. They were not allowed to take our money and give to customers a written (41) ______,because the sales wouldn‟t then have been recorded on the computer system. In the end, (42) _______many other people, I left my shopping on the counter and walked out .Don't you think so that's ridiculous? It (43) ________ never have happened before computers, and that, for me, is the problem: we are beginning to depend on these machines so completely that we (44) _______ cannot manage without them anymore.
Điền vào ô 40
Mark the letter A, B, C or D on your answer sheet to indicate the word or phrase that is OPPOSITE in meaning to the underlined part in each of the following questions.
The organization was established in 1950 in the USA.
Choose the best answer:
My younger sister is very __________ and so she loves going out but I am much quieter and prefer to stay at home.
Choose the best answer:
We stopped for a rest after we __________ for two hours
Choose the best answer:
_____ in UNESCO‟s World Heritage Sites in 2003, Phong Nha Ke Bang is noted for its cave and grotto systems.
Choose the best answer:
Going to the pub too often can easily become a bad __________
