题目内容
The pH of polluted rainwater ranges from about 6 to just below
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听力原文：W: Bob said that Seattle is a great place for conferences.
M: He's certainly in a position to make that comment. He's been there so often.
Q: What does the man say about Bob？
(14)
Pollutants are substances which, when present at high enough concentrations, produce harmful 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 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, 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 formation 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 micrometres 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 with 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 particles 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. Photochemical 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 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 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 people's main exposure to air pollutants occurs when they are indoors, such as at home, in the workplace or in entertainment 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 detectors, 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 ideal for remote use. Nitrogen dioxide, sulfur dioxide, ammonia and oth
Section A
Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the conversation and the questions will be spoken only once. After each question there will be a pause. During the pause, you must read the four choices marked A, B, C and D, and decide which is the best answer.
听力原文：W: Simon, could you return the tools I lent you for building the bookshelf last month？
M: Uh, well, I hate to tell you this.-- but I can' t seem to find them.
Q: What do we learn from the conversation？
(12)
如右图所示，以下对赢得值法参数分析正确的是()。
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