Sit on the desk,please.如何改为否定句

Sit on the desk,please.如何改为否定句 英语肯定变否定把Sit on the desk ,please 改为否定 Sit on the desk变为否定句 把下列祈使句变成否定句.1.Give me four stamps,please.2.Sit on the desk,p draw on the ,please.改为否定句 改为否定句 The math books are on the desk. The math books are on the desk.改为否定句 改为否定句,The math books are on the desk. Are the books on the desk?改为否定句 sit down,please 改为否定句 The keys are on the desk(改为否定句) The keys( )( ) on the desk. there in a light on the desk.改为否定句