1. ---Is this your pencil? --- No, it isn’t. It’s mine.
2. --- Is that his schoolbag? --- No, it isn’t. It’s hers.
3. ---Are these your books? --- Yes,they are. They are mine。
4. ---Are those his pencils? --- No, they aren’t. They are hers.
5. ---Thank you for your help. --- You are welcome.
这是谁的?    Whose is it?
这是我的。    It’s mine.
这是你的吗?    Is this yours?
是的。    Yes. it is.
不是的。    No. it isn't.