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

Never stop learning because the world never stops changing.

You can't cross the sea merely by standing and staring at the water.

晏子春秋

In the quest to understand quantum gravity, we are like children playing on the shore of a vast ocean, occasionally finding a smooth pebble or a pretty shell, while the great ocean of truth lies undiscovered before us.