it is not应该接difficult的什么形式

it is not应该接difficult的什么形式 it is not big it is not my it is not it is not goodbye it is not It is not.,but. It is not ( )you no,is it not It is not you ,()it? what i do not know is that why...是不是应该改为is it that why啊 it is pretty,is not it? It is not yours,it is mine. It is ( )ruler.It is not( )eraser. China now is not what it used to be.中文应该怎么翻译啊? that s____ wonderful,but it is not true.中应该填什么? it is not easy.这句话应该怎么问 why is it not easy?还是 why isn't it easy 问什么it is not easy.这句话应该怎么问why is it not easy?还是why isn't it easy问什么 what a bad day,_____?A.it is B.is it C.it is not D.isn't it 应该选哪个呢?what a bad day,_____?A.it is B.is it C.it is not D.isn't it 应该选哪个呢?