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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 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.The word “localized” in the third paragraph is closest in meaning to _____.
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 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.According to the passage, human-generated air pollution in localized regions _____.
Read the following pasage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questionsAny list of the greatest thinkers in history contains the name of the brilliant physicist Albert Einstein. His theories of relativity led to entirely new ways of thinking about time, space, matter, energy, and gravity. Einstein's work led to such scientific advances as the control of atomic energy, even television as a practical application of Einstein's work. In 1902 Einstein became an examiner in the Swiss patent office at Bern. In 1905, at age 26, he published the first of five major research papers. The first one provided a theory explaining Brownian movement, the zig-zag motion of microscopic particles in suspension. The second paper laid the foundation for the photon, or quantum, theory of light. In it he proposed that light is composed of separate packets of energy, called quanta or photons, that have some of the properties of particles and some of the properties of waves. A third paper contained the "special theory of relativity" which showed that time and motion are relative to the observer, if the speed of light is constant and the natural laws are the same everywhere in the universe. The fourth paper was a mathematical addition to the special theory of relativity. Here Einstein presented his famous formula, E = m(cc), known as the energy mass equivalence. In 1916, Einstein published his general theory of relativity. In it he proposed that gravity is not a force, but a curve in the space-time continuum, created by the presence of mass. Einstein spoke out frequently against nationalism, the exalting of one nation above all others. He opposed war and violence and supported Zionism, the movement to establish a Jewish homeland in Palestine. When the Nazis came to power in 1933, they denounced his ideas. He then moved to the United States. In 1939 Einstein learned that two German chemists had split the uranium atom. Einstein wrote to President Franklind. Roosevelt warning him that this scientific knowledge could lead to Germany developing an atomic bomb. He suggested the United States begin its own atomic bomb research.According to Einstein, light is composed of separate packets of energy called
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. The cause of tooth decay is acid, which is produced by bacteria in the mouth. The acid removes minerals from tooth enamel, allowing tooth decay to begin; the saliva in your mouth encourages remineralization and neutralizes the acid. The rate at which bacteria in the mouth produce acid depends on the amount of plaque on the teeth, the composition of the microbial flora, and whether the bacteria of the plaque have been "primed" by frequent exposure to sugar. To keep your teeth healthy, a regular dental hygiene program should be followed. Removing plaque with a toothbrush and dental floss temporarily reduces the numbers of bacteria in the mouth and thus reduces tooth decay. It also makes the surfaces of the teeth more accessible, enabling saliva to neutralize acid and remineralize lesions. If fluoride is present in drinking water when teeth are forming, some fluoride is incorporated into the enamel of the teeth, making them more resistant to attack by acid. Fluoride toothpaste seems to act in another way, by promoting the remineralization of early carious lesions.In addition to a regular dental hygiene program, a good way to keep your teeth healthy is to reduce your intake of sweet food. The least cavity-causing way to eat sweets is to have them with meals and not between. The number of times you eat sweets rather than the total amount determines how much harmful acid the bacteria in your saliva produce. But the amount of sweets influences the quality of your saliva. Avoid, if you can, sticky sweets that stay in your mouth a long time. Also try to brush and floss your teeth after eating sugary foods. Even rinsing your mouth with water is effective. Whenever possible, eat foods with fiber, such as raw carrot sticks, apples, celery sticks, etc., that scrape off plaque, acting as a toothbrush. Cavities can be greatly reduced if these rules are followed when eating sweets.What does this passage mainly discuss?
Read the following pasage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questionsAny list of the greatest thinkers in history contains the name of the brilliant physicist Albert Einstein. His theories of relativity led to entirely new ways of thinking about time, space, matter, energy, and gravity. Einstein's work led to such scientific advances as the control of atomic energy, even television as a practical application of Einstein's work. In 1902 Einstein became an examiner in the Swiss patent office at Bern. In 1905, at age 26, he published the first of five major research papers. The first one provided a theory explaining Brownian movement, the zig-zag motion of microscopic particles in suspension. The second paper laid the foundation for the photon, or quantum, theory of light. In it he proposed that light is composed of separate packets of energy, called quanta or photons, that have some of the properties of particles and some of the properties of waves. A third paper contained the "special theory of relativity" which showed that time and motion are relative to the observer, if the speed of light is constant and the natural laws are the same everywhere in the universe. The fourth paper was a mathematical addition to the special theory of relativity. Here Einstein presented his famous formula, E = m(cc), known as the energy mass equivalence. In 1916, Einstein published his general theory of relativity. In it he proposed that gravity is not a force, but a curve in the space-time continuum, created by the presence of mass. Einstein spoke out frequently against nationalism, the exalting of one nation above all others. He opposed war and violence and supported Zionism, the movement to establish a Jewish homeland in Palestine. When the Nazis came to power in 1933, they denounced his ideas. He then moved to the United States. In 1939 Einstein learned that two German chemists had split the uranium atom. Einstein wrote to President Franklind. Roosevelt warning him that this scientific knowledge could lead to Germany developing an atomic bomb. He suggested the United States begin its own atomic bomb research.It is clear from the tone of the passage that the author feels