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

We shall never prevent the abuse of power if we are not prepared to limit power in a way which occasionally may prevent its use for desirable purposes.

可持續的森林是既能支持野生動物又能維持生計的森林。

The writer's task is not to judge, but to understand.

The causal model is the key to making sense of the world.

數學不是一項觀賞性運動。你必須參與其中。

知識最大的敵人不是無知，而是以為自己知道。