单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. The application has a window named MainWindow that has a StackPanel control named sp as the root element. You want to create a Button control that contains a TextBlock control with the "Save" Text property. You need to create the control dynamically and add the control to sp. Which code segment should you write in the constructor of the MainWindow class?（）

单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You create a window that contains a Button control and a MenuItem control. Both controls are labeled "Add sugar." The Command properties of the Button and MenuItem controls are set to the same RoutedCommand named AddSugarCommand. You write the following code segment. private void CanAddSugar (object sender, CanExecuteRoutedEventArgs e) { ... } You need to ensure that when the CanAddSugar method sets e.CanExecute to false, the MenuItem and Button controls are disabled. What should you do?（）

多项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. The application contains a composite user control that includes a TextBox control named txtInput. The user control will be hosted in a window and will have handlers for the text-changed event of txtInput. You need to ensure that the application meets the following requirements: AddHandler(TextBox.TextChangedEvent, new RoutedEventHandler(Audit_TextChanged), true); Which of the following statments are TRUE ?（）