Answer the following questions according to the text.
1．According to the passage, what’s the gift for the future?
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参考答案：Sustainable development.
2．What is sustainable development?
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参考答案：Sustainable development focuses on preserving the environment and natural resources. It is a form of development which tries to protect Earth as well as improve standards of living.
3．Why is it important to look after the environment?
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参考答案：If we do not look after the environment, the lives of our children and grandchildren will be in danger. There will be an increase in pollution and acid rain.
4．Why should we use alternative energy sources?
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参考答案：By using alternative energy sources we can protect the environment. Besides, alternative energy sources can be used without running out.
