说明：  在C#中，产生一般随机数用Random即可，但是，若要产生服从特定分布的随机数，就需要一定的算法来支持了，产生服从正态分布、泊松分布、指数分布以及负指数分布随机数的方法
(A general random number in C#, you can use Random, but to have to obey a particular distribution of random numbers, you need a certain algorithm to support, resulting in a normal distribution, Poisson distribution, exponential distribution and negative exponential distribution the method of random number)