看图，完成对话。 1. —Where are the _____? —They're_____the_____. 2. —Where are the_____? —They're _____the_____ _____. 3. —Where is the_____? —It's_____the_____. 4. —Is this a bookcas? —_____,_____ _____. —What's it? —It's a_____. 5. —Are those books under the _____? —No,_____ _____. —Where are_____? —_____ _____the_____. 6. —Where are his pencils? —They are_____(on, at) the dresser. 7. There is a set of keys_____(in, on) the drawer. 8. —Is the baseball_____ (in, under) the bed? —No, it's under the chair. 9.The books are_____(under, in) the bag.