public class Class1
{
    //常量
    public const string URL = "http://www.mzwu.com/";

    //枚举
    public enum Sex { Boy, Girl }

    //委托
    public delegate void EventHandler(object sender, EventArgs e);

    //结构
    public struct Student
    {
        //姓名
        public string Name;
        //年龄
        public int Age;
    }

}

MessageBox.Show(Class1.URL);
MessageBox.Show(Class1.Sex.Girl.ToString());
Class1.Student student = new Class1.Student();
Class1.EventHandler eventHandler = new Class1.EventHandler(Test);