class Person
{
    string name;
    int age;
    {
        public Person(string _name, int _age)      //构造函数只带两个参 
        {                                                                      
            name = _name;                                                     
            age = _age;                                                        
         }                                                                   
        public void Parameters(string _name, int _age, double weight)   //定义方法可以自带三个参
        {
            Console.WriteLine("NoOne:"+_name+","+_age","+weight)
         }
         Person people = new Person("Zhangsan",22);   //这里只可以带二个参数
         people.Parameters("Lisi",23,60);             //三个参都能输出
我想问的是:1:构造函数只带了两个参数, 定义方法怎么可以带三个参数?   
            2:结构里面结构里面并没有weight它也能输出。
            但是把结构里的 name = _name;  改成  name = iname;    
                           age = _age;    改成  age = iage;      
            错误显示:当前上下文中不存在名称 iname,iage 
            两者都不能输出.这是为什么?