3.1:
1. What I was most glad with was the service of this shop.
2. It’s the loud music that I can’t stand.
3. It was June who didn’t pay for the meal.
4. What really annoys me is that he’s always late for work.
5. Was it you who chose the uniform?
3.2:
1. who
2. that
3. that
4. that
5. that
3.3:
1. It is my father who usually complains about my students whenever they go to my house.
2. It was I that/who used to like climbing up tress and pick fruits.
3. It is my neighbors who always make noise at night.
4. It is we that often complain about the noise at night.
5. It was you/that who gave her a bunch of rose last week.
6. It is our English teacher who/that is the greatest teacher in the world.
7. It was the earthquake that destroyed everything two years ago.
8. It is my recent computer that helps me a lots in preparing tasks for my students.
9. It was my student’s bad behavior that made me sad yesterday morning.
10. It was the man who gave her the book.
11. It was the boy who visited his uncle last month.
12. It was I and she who sang together at the party.
13. It was Nam’s father who got angry with him.
14. It was the boys played football all day long.
15. It was the girl who received a letter from her friend yesterday.
16. It was his presence at the meeting that frightened the children.
17. It was my mother who bought me a present on my birthday party.
18. It was the neighbor who told them about it.
19. It was my friend who came to see me late last night.
20. It was that boy who scored the goal for his team.
21. It was the dog that grabbed at the piece of meat and ran away.
22. It was the strong wind that blew the roof off.
23. It is her dog that my younger sister always keeps carefully.
24. It is the dog that the boy hit in the garden.
25. It was the man whom the answered rudely.
26. It was the ping pong that the boy played the whole afternoon.
27. It was a special gift that the girl gave the boy on his birthday.
28. It was this T-shirt that my wife gave to me on my last birthday party.
29. It is your picture that I always keep besides me.
30. It is in this restaurant that we often gather for dinner.
31. It is in the garden that the boy hit the dog.
32. It was from that corner shop that he bought the book.
33. It was at the shop that she bought him a present.
34. It is for tea that she makes some cakes.
35. It was for him that his father repaired the bicycle.