在C#中,下列代码的运行结果是( )。 public class Teacher { public int age; public Teacher(int age) { this.age=age; } public void ChangeAge(int age) { age++; } public void ChangeAge(Teacher tea) { tea.age++; } public static void Main() { Teacher tea=new Teacher(18); Console.WriteLine(tea.age); tea.ChangeAge(tea.age); Console.WriteLine(tea.age); tea.ChangeAge(tea); Console.WriteLine(Tea.age); } }