Sustainability is not an option; it's a responsibility we owe to future generations.
煤炭的真正成本不仅在于价格,还在于我们如何管理其后果。
你不可能教一个人任何知识, 因为你只能帮助他自己去找他想学的。
The detection of gravitational waves has opened a new window to observe the universe.