—— 请按键盘 空白键 开始游戏 ——

The PAC learning framework provides a formal way to quantify the learnability of a concept class.
用心体会整理才能理解精确得当,所以应当沉着稳重,不然就成了口头耳边的小事,过后就忘了。事理要以典故为依据,因此必须学识广博,否则就成了随意推测,胡编乱造。
Courage doesn't always roar. Sometimes courage is the quiet voice at the end of the day saying, "I will try again tomorrow."