说明：  计算机里的 RAN() 随机函数一般都是用软件方法“计算”得来的,也就是说它不是真正的随机数序列,——也就叫“伪随机”数,
(The RAN () random function in a computer is usually "calculated" by software, which means it is not a real sequence of random numbers, which is called "pseudorandom".)