1. 用方框中所给单词的适当形式填空。

her      I       box       this           you

1. （1） Are those your pencil ?
3. （2） —Is that green eraser Anna's?

   —No, it isn't. The yellow eraser is .

5. （3） Are your keys?

   No, they aren't

7. （4） — Is the blue pencil, Jenny?

   —No, It isn't.

9. （5） This schoolbag isn't. It's Helen's.