今天我们必须负责任地开采煤炭，这样我们的孩子才能继承能源安全和健康的环境。
We must mine coal responsibly today so that our children inherit both energy security and a healthy environment.
The essence of mathematics lies in its freedom.
The power of causal reasoning is that it allows us to predict the effects of actions we have never taken.
不要让成功冲昏头脑，也不要让失败打击你的心。
可持续性已不再是选择，而是我们对后代的责任。