色多多在线观看播放-色多多在线观看高清免费-色多多在线观看视频-色多多在线看-欧美aaaaa性bbbbb小妇-欧美aaaav免费大片

Data without insight is just noise.

"Books are the quietest and most constant of friends; they are the most accessible and wisest of counselors, and the most patient of teachers."

學習之道，沒有什么比能夠弄清事物的始末，來龍去脈更重要的。