this is his ring改成否定句

this is his ring改成否定句 This is his backpack.改成否定句 this is my ring改成同义句 Is this ring red.(作否定句) Is this his sharpener?改成肯定句 还有That is her ruler改成否定句! this is her ring改为否定句 __ __her ring.怎么改? this is my ruler改成否定句 This is a pagoda.改成否定句 this is my eraser.改成否定句 This is a dog改成否定句 Is this a dictionary?改成否定句 Is this his pen 改成同义句