1. Fossil fuels will be exhausted within a relatively short time.

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2. Geothermal heat is available only in a few places in the world.

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3. If the wind does not blow, there is no wind energy.

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4. Water power provides energy without pollution.

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5. A nuclear reactor releases radiation which is dangerous to the environment.

 ✓

6. Solar energy is not only plentiful and unlimited but also clean and safe.

 ✓

7. It is expensive to build a dam for hydroelectricity.