单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You add a DataGrid named gridContacts that is data-bound to a collection of Contacts. Each item has the ContactName and Phone properties. The DataGrid contains a column named ContactNameColumn that is bound to ContactName. You write the following code fragment. You need to ensure that the application meets the following requirements: Phone number is shown as a row detail when the row is selected. Only ContactName can be edited. What should you do?（）

单项选择题 You use Microsoft .NET Framework 4 to create a Windows application. You use ClickOnce technology to install the application on computers that run Windows 7 with User Access Control (UAC) enabled. The application requires access to environment variables on each computer. You need to ensure that users who do not have administrative permissions can install the application. Which deployment method should you use? （）

单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You add a TreeView control to show the hierarchical structure of orders and order details. Each order contains an ObservableCollection named OrderDetails. You write the following code fragment. (Line numbers are included for reference only.) You need to ensure that the TreeView control meets the following requirements: Each order is shown as a TreeView node. The order nodes have order detail nodes as children. The order detail nodes have no children. Which code fragment should you insert at line 07?（）