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A．It hurts our eyes.B．It hurts our skin.C．It is harmful to our respiratory system.D．It
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A．By good sense of water waves made by quarries.B．By good sense of smell and electrica
Section B
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.
A country is said to become more urbanized as its cities grow in number, its urban populations increase in size, and the proportion of its population living in urban areas rises. The degree of urbanization varies across the world but generally reflects the wealth of individual countries. The rich, industrialized countries tend to be the most highly urbanized. In the Netherlands, for example, 89 percent of the population is urban, compared to only 13 percent in Ethiopia, a much poorer country.
In recent history, the degree of urbanization has been relatively low in Africa and Asia compared to Europe and North America. However, as a result of large-scale migration from rural areas and a natural increase in the urban populations themselves, the populations of cities in the developing world have been growing rapidly. The population of Cairo, for example, has tripled in the last 40 years, and more than half of Africa's people are expected to be living in cities by 2020. Similarly, the urban share of the population in China has risen from about one in five in 1960 to nearly half today.
One of the most noticeable features of urban growth in the 20th century has been the rapid increase in the number of very large cities. Before 1800, cities with more than a million inhabitants were rare. Since then, however, the number of such cities has risen steadily. In 1900 there were at least 13 cities with more than a million inhabitants, and by 1950 the number had grown to 68. By 2000 there will be at least 250 cities of more than a million--many of which will be in Asia, especially in India and China.
Even a city of a few million people is dwarfed by the urban giants with populations exceeding 10 million. According to various estimates, there may be 20 or more of these gigantic metropolitan areas already. Most are in Asia: Tokyo, Seoul, Osaka, Shanghai, Mumbai (Bombay), Beijing, Calcutta, Jakarta, Tianjin, Karachi, Delhi, and Manila. The other giants are New York, Sao Paulo, Mexico City, Los Angeles, Moscow, Buenos Aires, Rio de Janeiro, and Cairo. In coming years, explosive growth in cities of the developing world such as Lagos and Santa Fe de Bogotá will almost certainly propel them into this group. By the year 2020, several cities are expected to have populations of more than 20 million.
Such large concentrations of people pose immense environmental problems. In Mexico City, for example, one-quarter of the population has no access to running water, and one in five houses is not connected to the sewerage system. Located in a valley, the city suffers so badly from air pollution from motor vehicles that the city center must periodically be closed to traffic. Mexico City's problems are replicated in most other large cities in the developing world, and to a lesser degree in the large cities of industrialized countries as well.
A country's urbanization can be seen from its increase in______.
听力原文： Scientists say sharks have lived in the world's oceans for millions of years. Scientists say there are more than three hundred and fifty different kinds of sharks.
Sharks do not have bones, and a shark has an extremely good sense of smell. It can find small amounts of substances in the water, such as blood, body liquids and chemicals produced by animals. Sharks also sense electrical and magnetic power linked to nerves and muscles of living animals. These powerful senses help them find their food. Some sharks will eat just about anything. Many unusual things have been found in the stomachs of some tiger sharks. They include shoes, dogs, a cow's foot and metal protective clothing.
About forty percent of the different kinds of sharks lay eggs. The others give birth to young. Some sharks carry their young inside their bodies like humans do.
Scientists are beginning to understand the importance of sharks to humans. Medical researchers want to learn more about the shark's body defense system against disease. They know that sharks recover quickly from injuries. Sharks appear never to suffer infections, cancer or heart diseases.
(33)
听力原文：M: Ozone is an extremely active gas comprised of three atoms of oxygen. Ozone exists naturally in the Earth's upper atmosphere, the stratosphere, where it shields the Earth from the sun's ultraviolet rays. However, ozone found close to the Earth's surface, called ground-level ozone, is a component of smog and a harmful substance.
W: What is the ground-level ozone？ Where does it come from？
M: Ground-level ozone is a colorless gas that can be found in the air we breathe. It is formed through a complex chemical reaction between volatile organic compounds and nitrogen oxides in the presence of sunlight. It is hard to be watched by eyes.
W: Who is considered most at risk from exposure to ground-level ozone？
M: Children are the most at risk from exposure to ground-level ozone: Their respiratory systems are still developing and they breathe more air per pound of body weight than adults.
W: From what you've just said, can I infer that ground-level ozone is closely related to summer, the hot days？
M: Ground-level ozone is a summer time problem; children spend most of the summer outside playing at summer camps, playgrounds, and neighborhood parks and in backyards.
W: How do I know when ground-level ozone concentrations are high？
M: Ground-level ozone concentrations tend to be especially high during summer when the weather is hot and sunny.
W: Is there any organization providing relevant information？
M: The staff from the departments concerned has developed a procedure to inform. the public about expected ground-level ozone readings. Each afternoon from May 1st through September 15th, the staff retrieve and review monitored ozone data and weather forecast information. Then they develop ground-level ozone forecasts for the following day.
(23)
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