单项选择题 You create a Windows client application by using Windows Presentation Foundation (WPF). The application contains the following code fragment. You need to assign lbDetails to use the detail data template when btnDetails is clicked. Which code segment should you write for the click event handler for btnDetails?（）

单项选择题 You are developing a Windows Forms application that contains a DataGridView control. The DataGridView capture the customers name, address, and phone number. You have been asked to provide data validation in a DataGridView to prevent users from leaving the.. You need to ensure that users cannot tab out of the name field without entering data What should you do ?（）

单项选择题 You use Microsoft .NET Framework 4 to create an application. The application performs resource-intensive calculations that consist of multiple layers of nested looping. The application will be deployed to servers that contain varying hardware configurations. You need to ensure that the application utilizes CPU resources on the server in the most efficient manner. You want to achieve this goal by using the minimum amount of code. What should you do?（）