Legal obligations are not merely moral obligations backed by sanctions.
如果你不冒险，你永远不会知道自己真正的潜力。
The study of black holes has revolutionized our understanding of space and time.
Never stop learning, because the world never stops changing.
艺术不是关于再现；而是关于在场。
The strength of a response tendency depends on the amount of reinforcement received.