PAC学习框架提供了一种形式化的方法来量化概念类的可学习性。
The PAC learning framework provides a formal way to quantify the learnability of a concept class.
当准备遇到机会时，成功就会到来。
On television， all subject matter must be presented as entertainment.
水边的芦苇夜间结霜，月色寒冷与山色一同显得苍茫。
The sea is a mirror of the soul—endless, shifting, and unfathomable.