you must finish your homework today.改成否定句.

You don't need to finish your homework today./ You needn't finish your homework today.
过程和思路就是,改成否定句要加否定词,must 的否定是 needn't 因为mustn't的意思是不许,不准,不是不必.所以用needn't或者don't need to.
再问： 一个一词。这里一个空