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煤炭的真实成本必须既考虑其即时价值,也考虑其对社区和生态系统的长期影响。
"I think the best way to encourage children to read is to give them books that they can't put down."
The intersection of mathematics and computer science is where some of the most exciting discoveries are made.
世界上充满了门,每一扇门都是一个选择。