1、--What's that __on__the wall? --It's a picture _in__a classroom.
2、We can see four windows __on_the wall _of__the classroom.
3、The ball is _under_the bed , and the broom is _behind__the door.So you can't see them.
4、Look _at_the picture _of__my family. The boy _next to_my parents is me.
5、There are some birds _in_the tree.Can you see them?