Sit on the desk变为否定句

Sit on the desk变为否定句 Sit on the desk,please.如何改为否定句 The are some magazines on the desk变为否定句? There is a book and a pen on the desk.(变为否定句) There are some flowers on the teacher’s desk.(变为否定句) There is a book 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 英语肯定变否定把Sit on the desk ,please 改为否定 The keys are on the desk(改为否定句) The keys( )( ) on the desk. put the pens on the desk .(变为否定句） ————— ——————— the pena on 改为否定句 The math books are on the desk. The math books are on the desk.改为否定句