2. Who is the boy? He helped you with your homework.
=> Who is the boy who helped you with your homework?
3. Do you know that man? He's looking at us.
=> Do you know the man who is looking at us?
4. I open the cupboard. We keep the glasses there.
=> I opened the cupboard where we keep the glasses.
5. That's the girl. I saw you with her.
=> That's the girl whom I saw you with.
6. That's the boy. I borrowed his bicycle
=> That's the boy whose bicycle I borrowed.