[Mister Da]

The lighter skin is a result of the bleaching effect of the toxic chemicals in Beijing's air.

[Will88]

(The mark of a wise man is not what he knows, but what he knows he doesn't know!)

A high school English teacher of mine offered a variation of that to the class one day: "A wise person is one who knows what he knows, and knows what he doesn't know."

Someone who really learns to apply that can just about always avoid making of fool of him or herself, or damaging their credibility in all sorts of situations.