将下列的单数句变为复数句，复数句变为单数句。1. They have many presents.

2. There is a boy in the classroom.

3. That is Lucy's pencil-box.

4. My uncles go to work by bike.
1. He/She has a present.
2. There are many boys in the classroom.
3. Those are Lucy's pencil-boxes.
4. My uncle goes to work by bike.