The P versus NP problem is one of the most important unsolved problems in computer science.
黑洞不仅仅是破坏性的怪物,它们在塑造星系中起着关键作用。
It's waiting that helps you as an investor and a lot of people just can't stand to wait.If you didn't get the deferred -gratification gene, you've got to work very hard to overcome that.