/// <summary>
 /// 减少金额.
 /// </summary>
 /// <param name="a"></param>
 /// <param name="amt"></param>
 public void SubCash(Account a, double amt)
 {
     Console.WriteLine("减少金额:{0}", amt);
     a.Cash -= amt;
 }
 /// <summary>
 /// 减少金额.
 /// </summary>
 /// <param name="a"></param>
 /// <param name="amt"></param>
 public void SubCash(Account a, double amt)
 {
     Console.WriteLine("日志:减少金额:{0}", amt);
 }
 /// <summary>
 /// 增加金额.
 /// </summary>
 /// <param name="a"></param>
 /// <param name="amt"></param>
 public void AddCash(Account a, double amt)
 {
     Console.WriteLine("增加金额:{0}", amt);
     a.Cash += amt;
 }
 /// <summary>
 /// 增加金额.
 /// </summary>
 /// <param name="a"></param>
 /// <param name="amt"></param>
 public void AddCash(Account a, double amt)
 {
     Console.WriteLine("日志:增加金额:{0}", amt);
 }