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 a spectator sport.

Globalization is not a multiple-choice question, but a required question.

The best books are those that leave you changed.

I’m not perfect, but I’m trying my best.

History is not the past. It is the method we have evolved of organizing our ignorance of the past.