Ответ:

3. Compound nouns:

  1. Sit in the waiting room.
  2. My sister had an accident but there was someone there who knew first aid.
  3. She ate something bad and now she's got food poisoning.
  4. Take this painkiller three times a day if your back hurts.
  5. My neighbour is a doctor at the medical centre down the road.
  6. Quickly! Get a doctor. I think this man is having a heart attack.