单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a page that contains the following control：   <asp：Calendar EnableViewState="false" ID="calBegin" runat="server" />    You write the following code segment in the code-behind file for the page：   void LoadDate（object sender， EventArgs e） {   if （IsPostBack） {   calBegin.SelectedDate = （DateTime）ViewState["date"]；   }  }    void SaveDate（object sender， EventArgs e） { ViewState["date"] = calBegin.SelectedDate；   }   You need to ensure that the calBegin Calendar control maintains the selected date.  Which code segment should you insert in the constructor of the page？（）

单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a Web page that has a GridView control named GridView1. The GridView1 control displays the data from a database named Region and a table named Location. You write the following code segment to populate the GridView1 control：   01 protected void Page_Load（object sender， EventArgs e）   02 {   03   string connstr；   04   05   SqlDependency.Start（connstr）；   06   using （SqlConnection connection =   07     new SqlConnection（connstr））   08   {   09     SqlCommand sqlcmd = new SqlCommand（）；   10     DateTime expires = DateTime.Now.AddMinutes（30）；   11     SqlCacheDependency dependency = new   12       SqlCacheDependency（"Region"， "Location"）；  13     Response.Cache.SetExpires（expires）；   14     Response.Cache.SetValidUntilExpires（true）；   15     Response.AddCacheDependency（dependency）；   16   17     sqlcmd.Connection = connection；   18     GridView1.DataSource = sqlcmd.ExecuteReader（）；   19     GridView1.DataBind（）；   20   }   21 }  You need to ensure that the proxy servers can cache the content of the GridView1 control.  Which code segment should you insert at line 16？（）

单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a custom Web user control named SharedControl. The control will be compiled as a library.  You write the following code segment for the SharedControl control： 01 protected override void OnInit（EventArgs e）   02 {   03   base.OnInit（e）；   04   05 }    All the master pages in the ASP.NET application contain the following directive. <%@ Master Language="C#" EnableViewState="false" %>    You need to ensure that the state of the SharedControl control can persist on the pages that reference a master page.  Which code segment should you insert at line 04？（）