使劲活下去，或使劲找死。
Hard to live or die hard.
The PAC learning framework provides a formal way to quantify the learnability of a concept class.
我喜欢表演，但我也喜欢独处。
Life is full of possibilities, death is final.
"Books are the quietest and most constant of friends; they are the most accessible and wisest of counselors, and the most patient of teachers."
应对不自由世界的唯一方法就是变得如此绝对自由，以至于你的存在本身就是一种反叛。