1. I know a woman. She makes locks and key.
⇒ I know a woman who makes locks and key.
2. My mother helps me with my housework.
⇒ It's my mother who helps me with my housework.
3. That's man. I told you about him yesterday.
⇒ That's a man who I told you about yesterday.
4. The boy injured in the accident was taken to the hospital.
⇒ The boy who injured in the accident was taken to the hospital.
5. Did the boy visit his uncle last month?
⇒ The boy visited his uncle last month, didn't he?
~Good luck~