单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You create a Button control for the application. You need to ensure that the application meets the following requirements: When the mouse pointer is over the Button control, the background color of the button is set to red and the Button control appears bigger. When the mouse pointer is not over the Button control, the button returns to its original state. What should you do?（）

单项选择题 You are developing a Windows Presentation Foundation (WPF) application. An event triggers a workflow such that a parent control executes the event handlers before the child controls. You need to ensure that if a parent controls event handler encounters an error, the subsequent handlers are not called. What should you do?（）

单项选择题 You are developing a Windows Presentation Foundation (WPF) application to play audio files. You add MediaElement mediaElement1 and a Button control named btnPlayAudio to the design surface. The MediaElement co.. audio file. The LoadedBehavior attribute is set to Manual. You add the following code to the main Window. You set the command of the button to MediaCommands.Play. You need to ensure that the application will play the audio file when the button is pressed. What should you add to constructor of the main window ?（）