阅读理解。

     In our lives, we enjoy everything from computers to cars to heated buildings. These comforts have

something in common: they all need energy to work. Energy has many different forms. One form, electricity,

comes mostly from steam-powered generators (蒸汽发电机). Steam is made by buming coal, oil, or natural

gas. Gasoline(汽油) is another form of energy. Casoline is made from oil. Oil has many other uses. Paints,

fertilizers, and plastics are made from it. We even use it to heat buildings. Coal, oil, and gas are natural

resources (资源). We take them from nature to make our lives easier.

     We can classify (分类) natural resources as either renewable or nonrenewable. Coal, oil, and gas are

nonrenewable. They take millions of years to form. Some scientists predict that we will run out of oil and

gas in 50 to 100 years. Coal is more plentiful. So it may last for hundreds of years. Resources such as wood

and water are renew- able. They can be grown or recycled naturally. They can, however, become limited

from overuse.

     We have developed some altemate (替代的) sources of energy. But these sources have disadvantages. For

example, hydroelectric power, or energy from running water, affects the ecology (生态) of surrounding areas.

Nuclear power (核电), another altemate source, presents the threat (威胁) of nuclear accidents. There are also

problems related to the storage (储存) of nuclear wastes. Solar and wind energies aren't consistent. We can't

depend on them. Geothermal energy, caused by heat from inside the earth, is tapped by drawing steam and

hot water from pools and geysers. This energy source, like most others, isn't fully developed.

      It's time to get serious about energy. We must find practical, alternate energy sources. If we wait too long,

it will be too late. We will run out of coal, oil, and natural gas. Then we won't have the resources to make

altemate energy sources.

1. Does oil have many uses? 

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2. How long may coal last according to the passage?

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3. Why are wood and water renewable resources? 

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4. What can be problems with nuclear power? 

    ________________________________________

5. What's the main idea of the passage? 

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