单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a login Web form by using the following code fragment：   <asp：ScriptManager ID="ScriptManager1" runat="server" />   <asp：TextBox runat="server" ID="txtUser" Width="200px" />   <asp：TextBox runat="server" ID="txtPassword" Width="200px" />   <asp：Button runat="server" ID="btnLogin" Text="Login"    OnClientClick="login（）； return false；" />    When a user clicks the btnLogin Button control， the login（） client-side script is called to authenticate the user. The credentials provided in the TextBox controls are used to call the client-side script.  You also add the following client-script code fragment in the Web form：   01 <script type="text/javascript">   02   function login（） {   03     var username = $get（’txtUser’）.value；   04     var password = $get（’txtPassword’）.value；   05   06    // authentication logic.  07   }   08   function onLoginCompleted（validCredentials， userContext，   09     methodName）   10   {   11     // notify user on authentication result.  12   }   13   14   function onLoginFailed（error， userContext， methodName）   15   {   16     // notify user on authentication exception.  17   }   18 </script>   The ASP.NET application is configured to use Forms Authentication. The ASP.NET AJAX authentication service is activated in the Web.config file.  You need to ensure that the following workflow is maintained：  on successful authentication， the onLoginCompleted client-script function is called to notify the user.  on failure of authentication， the onLoginFailed client-script function is called to display an error message.   Which code segment should you insert at line 06？（）

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 form by using ASP.NET AJAX. The Web form contains the following code fragment： 01 <script type="text/javascript">   02   03   Sys.Application.add_init（initComponents）；   04   05   function initComponents（） {   06   07   }   08   09 </script>   10   11 <asp：ScriptManager ID="ScriptManager1"   12   runat="server" />   13 <asp：TextBox runat="server" ID="TextBox1" />   You need to create and initialize a client behavior named MyCustomBehavior by using the initComponents function. You also need to ensure that MyCustomBehavior is attached to the TextBox1 Textbox control.  Which code segment should you insert at line 06？ （）

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 form by using ASP.NET AJAX.  You write the following client-script code fragment to handle the exceptions thrown from asynchronous postbacks：   01 <script type="text/javascript">   02   function pageLoad（）   03   {   04     var pageMgr =  05       Sys.WebForms.PageRequestManager.getInstance（）；   06   07   }   08   09   function errorHandler（sender， args）   10   {   11   12   }   13 </script> You need to ensure that the application performs the following tasks：  use a common client-script function named errorHandler.  udpdate a Label control that has an ID named lblError with the error message.  prevent the browser from displaying any message box or Javascript error.   What should you do？（）