单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5.  You write the following code fragment.  You need to ensure that when you click the btnSubmit Button control， each Label control value is asynchronously updatable.  Which code segment should you use？（）

单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5.  You write the following code fragment. You need to ensure that when you click the btnSubmit Button control， each Label control value is asynchronously updatable.  Which code segment should you use？ （）

单项选择题 You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. The application contains two Web pages named OrderDetails.aspx and OrderError.htm.  If the application throws unhandled errors in the OrderDetails.aspx Web page, a stack trace is displayed to remote users. You need to ensure that the OrderError.htm Web page is displayed for unhandled errors only in the OrderDetails.aspx Web page. What should you do? （）