Which three scenarios describe appropriate uses for key triggers?（）

• A、Alter data in a database table. 
• B、Add custom item validation code. 
• C、Disable the Next Block key and menu item. 
• D、Display a custom form in place of a List of Values. 
• E、Change the navigational order of the blocks in a form. 
• F、Perform a complex calculation each time the F10 key is pressed.