be as pure as the driven snow

as pure as the driven snow这个短语指的是道德上单纯、无辜的人。在暴风雪期间，雪不停地吹。因为没有人在上面行走，所以它被称为

driven snow，而它就是纯净的。因此，这个短语通常用来形容心地善良的人。你也可以用这个短语来说明一些物体描述它是白色或它的纯度。

to be morally completely good

(道德)纯洁无瑕

How dare he criticize me for having an affair? He's not exactly as pure as the driven snow himself.

他怎么敢指责我有外遇?他自己也不是纯洁无瑕的。