[外语类试卷]大学英语四级模拟试卷564及答案与解析.doc
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1、大学英语四级模拟试卷 564及答案与解析 一、 Part I Writing (30 minutes) 1 For this part, you are allowed 30 minutes to write a want ad for the School Magazine with the title Assistant Editor Wanted. You should write at least 120 words and base your composition on the following points: 1. duties and requirements of the
2、post 2. means of contact and other necessary information 二、 Part II Reading Comprehension (Skimming and Scanning) (15 minutes) Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions attached to the passage. For questions 1-7, mark: Y (for YES) if t
3、he statement agrees with the information given in the passage; N (for NO) if the statement contradicts the information given in the passage; NG (for NOT GIVEN) if the information is not given in the passage. 1 Pollutants are substances which, when present at high enough concentrations, produce harmf
4、ul effects on people and/or the environment. Sulfur dioxide Sulfur dioxide is produced when coal and oil are burnt or when minerals are “roasted“ to remove the sulfur. In some countries, particularly in the northern hemisphere, coal and oil contain significant amounts of sulfur. Unless special steps
5、 are taken to remove sulfur dioxide, it is released into the atmosphere. Power stations and industrial plants, which are often sited close to cities, can produce large quantities of the gas. As well as affecting human health, sulfur dioxide can be harmful to plants, turning leaves yellow and drying,
6、 bleaching, and even killing, foliage. In the atmosphere, sulfur dioxide can form acidic particles, or react with cloud droplets, contributing to acid rain. Particles Particles in the air come from a number of sources, including motor vehicles, industrial processes and wood burning. Secondary format
7、ion of particles(formation from gaseous emissions )can also contribute significantly to particle levels. Some atmospheric particles are from natural sources. These include wind-blown dust, pollen, sea salt, and material from volcanic eruptions. Fine particles(particles with a diameter of 10 micromet
8、res or less)can be inhaled deeply into the lungs and have been associated with a wide range of adverse respiratory symptoms. Long-and short-term exposure to such particles has been linked with increased deaths from heart and lung disease. Lead compounds, which are emitted by motor vehicles fuelled w
9、ith leaded petrol, are cumulative poisons. They slowly build up in the body. Urban haze Urban haze is mainly due to fine particles, which cause scattering or absorption of light. Haze is typically brown and limits visibility. Studies by CSIRO scientists have found that there are several types of par
10、ticles present in haze in Australian cities: organic carbon compounds, elemental carbon or soot, salt, sulfates, nitrates and dust. Photochemical smog Sometimes, under certain meteorological conditions, the combined effects of a number of air pollutants are worse than the individual effects. Photoch
11、emical smog, sometimes seen as a whitish haze present over cities during summer, is an example of this. Photochemical smog is formed on still days when the sun shines on air containing volatile organic compounds(VOCs)and oxides of nitrogen. Volatile organic compounds include hydrocarbons, as well as
12、 alcohols, aldehydes and ethers. VOCs in the air arise mainly from automotive fuels and industrial solvents. Chemical reactions driven by sunlight and involving VOCs and oxides of nitrogen form ozone, a gas harmful to humans, animals and plants. Air quality indoors Australians on average spend about
13、 ninety-five percent of their time indoors and many pollutants occur at higher concentrations indoors than outdoors because of the materials and appliances used in buildings. Many peoples main exposure to air pollutants occurs when they are indoors, such as at home, in the workplace or in entertainm
14、ent venues. Researchers are working towards measuring individual exposure to pollutants. That is, a measure of the actual exposure that people have to air pollutants during their daily routines, rather than measures of pollution at fixed locations. CSIRO regularly uses personal air pollution detecto
15、rs, which monitor concentrations of pollutants that people breathe. The inexpensive samplers offer scientists, environmentalists, engineers and others a simple but accurate way of measuring selected pollutants in air. The sampler, based on a Swedish design, is small and requires no electricity so is
16、 ideal for remote use. Nitrogen dioxide, sulfur dioxide, ammonia and other gases can be measured with the device. Acid rain Pure rainwater is slightly acidic, primarily because of dissolved carbon dioxide. Air also contains naturally occurring organic acids and acidic particles. The pH of unpolluted
17、 rainwater ranges from about 6 to just below 5. Fossil fuel combustion and industrial processes release into the air compounds containing oxides of sulfur and nitrogen. These compounds may then dissolve in cloud droplets, making rainwater more acidic. As well, sulfur-and nitrogen-containing particle
18、s may mix through the atmosphere, eventually coming into direct contact with the ground and vegetation. In other words, the pollutants can reach the ground in a wet or dry form. Both forms can harm soil, lakes, plants, buildings and people. Acidic pollutants released by one country can travel hundre
19、ds, or even thousands, of kilometres before being deposited. Acid rain is a real problem in Scandinavian countries, a large fraction being due to pollution released by other European countries. There is more industrial activity in the northern hemisphere than in the southern hemisphere. Industry als
20、o tends to be concentrated in particular regions. This is why acid rain problems are worse in the northern hemisphere. The main regions affected are north-western Europe and eastern United States and Canada. Japan and parts of China also have acidity problems. Air pollution in Australia Compared wit
21、h cities such as Los Angeles, Mexico City and Athens, air pollution problems in Australia are minor. In part, this is due to the fact that we have fewer sources of pollution, and local winds tend to rapidly disperse pollution over our cities. Australia has a relatively small population. We are surro
22、unded by oceans and do not receive masses of polluted air from other countries. Our oil and coal contain less sulfur than much of the oil and coal produced in other countries. Nevertheless, each year, Sydney, Melbourne and other large Australian cities experience days of high air pollution. Summer a
23、nd autumn are usually the worst times of the year. Reducing air pollution Government legislation and tighter emission controls by industry have produced a marked improvement in air quality in many parts of the world. Many methods of lowering emissions have been developed. In Australia, the emphasis
24、is on prevention and early identification of air quality problems. Domestic burning off adds to air pollution. In Australian cities, many municipalities have banned the use of incinerators. Agricultural and forest management practices that do not involve burning can also reduce the release of visibi
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