—I would like you to talk about the Great Wall. —I’m sorry, but _________ Jack _________ I have been there.
---Your English is very good. --- ___________.
--- Are these your books? --- No, they aren’t. They are ____________.
--- _________, where’s my pen? --- __________, I don’t know.
---How many _______do you have? ---Let me see, my father has two brothers.
--- Is that your backpack? --- __________. It’s my backpack.