The most important things are hardest to tell,because words shrink their importance.It's not easy to let strangers care about the good things in your life.

翻译：天地运行的法则，是恒久不息的。

Entrepreneurs should have a sense of social responsibility.

"The power of literature lies in its ability to make the invisible visible and the silent heard."

The PAC learning framework provides a formal way to quantify the learnability of a concept class.