一幅画永远不会完成，只会被放弃。
A painting is never finished, only abandoned.
不要看时钟；做它所做的。继续前进。
We will now discuss in a little more detail the Struggle for Existence.
Understanding black holes is understanding the fabric of the universe itself.
About 99% of the time， the right time is right now.
Everything that happens once can never happen again. But everything that happens twice will surely happen a third time.