句型：- Whats this?- Its a book. - How do you spell that?- Its B-double O-K- Is this your book?- Yes, it is. Its my book. 句型练习 This is my book. These are my books. That is your eraser. Those are your erasers. Is this your calendar? Are these your calendars Is that your backpack? Are those your backpacks? Yes, it is. Yes, they are. No, it isnt. No, they arent. 语法重点：指示代词的用
