1. The girl are Nga and Hoa. They are playing chess.
->The girl the girls who are playing chess are nga and hoa
2. The taxi broke down. It was taking us to the airport.
->The taxi taking us to the airport
3. The student is very nervous. He is sitting next to me.
->The student sitting next to me was very nervous
4. The baby is crying for her mother. She is sitting in an armchair.
->The baby sitting in an armchair is crying for her mother.
5. Do you know the woman? The woman is talking to Tom.
->Do you know the girl whom Tom is talking to?
6. The boy was taken to the hospital. He was injured in the accident.
->The boy who was injured in the accident was taken to the hospital.