Ex2:

1. that

2. whose

3. why

4. whom

5. which

6. when

7. where

8. who/ that

9. who

10. which

Ex3: 

1. The examination which I was successful in lasted 2 days

2. The market which I usually go to has refresh vegetables

3. The man whom I told you about is over there

4. The film which they are talking about is fantastic

5. She is the nurse whom we gave the flowers to

6. The teacher whom we studied with last year is Mr Pike

7. That's the woman whom John used to be married

8. I like standing at the window where I can see the park from

9. The woman who you gave the place to on the bus lives next door to me

10. Mr Brown is the man who I'm responsible to for my work

Ex4: 

1. A

2. D

3. D

4. D

5. A

6. B

7. B

8. C 

9. B

10. C