解释：在人活动范围内的水就污浊，在野外无人地方的水就清洁。同为一样的水，都是从天边开源，有的混浊有的清洁，这是它们所处环境使它们这样的。

爱是最强大的灵感。

Only by continuous learning can we make continuous progress.

Your past does not define your future.

The deepest theorems often have the simplest proofs - if you look at them from the right angle.

每一个挑战都是学习和改进的机会。