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

Mathematics is not about numbers, equations, computations, or algorithms: it is about understanding.

It will take about a thousand million million million million years for the Earth to run into the sun, so there’s no immediate cause for worry!

The only thing that really matters is, are you a good person?

每個故事都有潛力去激勵、教育和娛樂。

最好的歌曲來自個人經歷。