单项选择题 You use Microsoft .NET Framework 4 to create a Windows Forms application. You have a dataset as shown in the following exhibit. You plan to add a DataGridView to display the dataset. You need to ensure that the DataGridView meets the following requirements: Shows Order Details for the selected order. Shows only Order Details for items that have UnitPrice greater than 20. Sorts Products by ProductName . Which code segment should you use? （）

单项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You write the following code segment. The TextBox control is data-bound to an instance of the Contact class. You plan to implement an ErrorTemplate in the TextBox control. You need to ensure that the validation error message is displayed next to the TextBox control. Which code fragment should you use?（）

多项选择题 You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You write the following code segment. (Line numbers are included for reference only.) The TextBox control is data-bound to an instance of the Contact class. You need to ensure that the Contact class contains a business rule to ensure that the ContactName property is not empty or NULL. You also need to ensure that the TextBox control validates the input data. Which two actions should you perform?（）