作业精灵老师示例：
Tina's friends come to see her. Tina shows
them around her home. They go into the
living room. It's big and clean. They go
into Tina's bedroom. It's small, but it's
nice. They go into Bobby's bedroom.
They see a lot of books and toys on the
floor. They cannot see Bobby. Where's
Bobby? He's under the bed. Bobby should
put his books and toys in order.
