定义一个按身高计算标准体重的类StdWeight，其中包含两个静态的成员方法：forMale(double h)计算男子标准体重、forFemale(double h)计算女子标准体重，两个方法均带返回值-Define a standard weight-height class StdWeight, which contains two static member method: forMale (double h) calculating the standard weight men, forFemale (double h) calculation of the standard weight woman, both of which are with the return value