To feed the world, we must first learn to respect the limits of our planet.
Sustainable development is not an option, but a necessity for the coal sector.
物理学的美丽在于它能够用简单的原理描述复杂的事物。
不能通过正式手段从非正式到正式。
Mathematics is not about numbers, equations, computations, or algorithms: it is about understanding.