/////form1.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
    }
}

///class.cs
namespace WindowsFormsApplication3
{
    class Class1
    {
        static public void test()
        {
            ////这里
            Label lab = Form1.
        }
    }
}