you must be right 否定句

句:You must (be joking). i think you are right.否定句 You must wait.(怎么改否定句) You must stop.改成否定句 You must wear uniforms.改否定句 You must pick the flower(否定句) must的否定句?A large hole must be dug.(否定句)A large hole ______be you may be right 同义句是什么? You must leave here right now.(同义句转换) Tom must be in his room.(改为否定句) 句型转换：It must be SARS.(变否定句） It must be a spaceship(改为否定句）