小于给定数的素数个数是该数的一个函数。
自由民主的未来取决于其适应新挑战并维持公民支持的能力。
Science fiction is the literature of change.
心有自己的记忆,而这种记忆并不总是与大脑商量。
The only limit to our realization of tomorrow will be our doubts of today.
The world is not a wish-granting factory.
The key to making money in stocks is not to get scared out of them.