The concept of NP-completeness has provided a powerful tool for understanding the complexity of problems.
真正的纽约人暗中相信,生活在其他地方的人在某种意义上一定是在开玩笑。
The true value of a forest can't be measured in board feet alone.
可持续性不是一种趋势,而是我们对下一代的责任。