单项选择题 You are creating a Windows Forms application for a book retailer by using .Net Framework 3.5.You are creating a Windows form to allow users to maintain a list of books. You write the following code segment. The variables strTitle and strISBN are already initialized with the necessary values. Which code segment should you insert at line 07？（）

单项选择题 You are creating a Windows Forms application using the .NET Framework 3.5.You implement the PrintPage page event for a form.The users must be able to print the pages by using the Landscape orientation.You need to ensure that the users can set the page settings before printing.    Which code segment should you use？（）

单项选择题 You are creating a Windows Forms application by using the .NET Framework 3.5. You write the following code segment to bind a list of categories to a dropdown list.  （Line numbers are included for reference only.） You need to ensure that the dropdown list meets the following requirements： （1）Displays all category names   （2）Uses the category ID as the selected item value     Which code segment should you add at line 06？（）