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最佳答案：The population problem resulting in water and energy shortages,the city is crowd
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最佳答案：I think we should treasure the food, energy, and offer our own strength in order
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最佳答案：How to put the energy to better use is one of the most important methods to solv
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最佳答案：scientists are trying to make better use of solar energy in order to solve energ
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最佳答案：Add to acquire new energy.Expanding living space.Huge cost.Astronauts safety pro
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最佳答案：In recent years, with the rapid development of economic construction, people's l
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最佳答案：With global warming to the survival and development of mankind, along with the s