编写两个类：A和B，A常见的对象可以计算两个正整数的最大公约数，B常见的对象可以计算两个数的最小公倍数。要求：B类中有一个成员变量时用A类声明对象.-Write two classes: A and B, A common object can be of two positive integers GCD computation, LCM B common object can be used to calculate the number of two. Requirements: have a member variable in the B class with a statement object。