关于昨天的问题

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
private int i = 0;
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
{
Response.Write("123");
}
}
protected void Button1_Click(object sender, EventArgs e)
{

}
}