The weight of the material determines the form.

随机实验是因果推理的黄金标准，但它们并不总是可行的。

Every tree planted today is a promise to tomorrow.

The heart of a mother is a deep abyss at the bottom of which you will always find forgiveness.

The paper industry has a responsibility to lead the way in sustainable practices—we can't wait for others to show us how.

解释：伟大而不骄傲，勤劳而不自夸有功。