在计算机科学中，我们总是在寻找表达能力和可处理性之间的平衡。
"In computer science, we are always trying to find the balance between expressiveness and tractability."
"You can't always get what you want, but sometimes, you get what you need."
The truth is: the natural world is changing. And we are totally dependent on that world. It provides our food, water and air. It is the most precious thing we have and we need to defend it.
