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

To see is to forget the name of the thing one sees.

A tannery’s legacy should be measured by its environmental stewardship.

"The magic of reading is that it allows us to live a thousand lives."

The universe is a vast and complex system, and understanding it requires both theoretical insights and observational evidence.

科學發現的影響可能是深遠的，往往遠遠超出最初的預期。

經濟學的目標是理解如何以最高效的方式分配稀缺資源。