Помогите пожалуйста расставить who либо which в предложении. Пример будет показан

1. Mister brown has two brothers who are scientists.

2. I will bright the dictionary which I bought yesterday.

3.  Here is the lady who has been to Madrid.

4. There is my mother who was a teacher at school.

5. The doctor will get you the medicine which will help you a lot.

6. I met the actor who had won the prize.

7. I will buy the toothbrush which was recommended by my dentist.

8. Last night I saw a dream which was terrible.

9. I will phone the manager who has promised to help me.

10. We stayed at a hotel which was very comfortable.

11. This is a hotel which I can recommend.

12. He will show you the photos which he took in Tula.

13. They will introduce me to the man who taught them how to drive.

14. She has two cousins who collect coins.

15. He showed me the coin which he wanted to give her as a present.

16. I met a student who knew a lot of subject.

17. I cut the pie which she had baked for us.

18. I'll introduce you to the lady who often visits the city.

19. Let's invite the man who will decorate the hall.