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

The teacher should not teach as if he were pouring knowledge into an empty vessel, but rather as if he were lighting a fire.

Companies must have long-term strategic vision and not focus solely on immediate gains.

數(shù)學(xué)教會我們同時進行邏輯和創(chuàng)造性的思考。