=>
IV/
1. unhappily
2. childhood
3. excited
4. successfully
5. competitors
6. flights
7. entertainment
8. behavior
9. proud
10. uncomfortable 

V/
1. A -> saying
2. B -> rang
3. A -> It's not difficult
4. B -> how to explain
5. B -> great
6. B -> took 
7. B -> from
8. C -> the greatest
9. D -> so did Jane
10. B -> to do

VI/
1. Unless the weather is bad, we will go away.
2. It is interesting to get out with friends at weekend.
3. My brother enjoys walking in the rain.
4. We haven't met each other for ten years.
5. They stopped playing tennis 5 years ago.
6. The date of the meeting will have to be changed again.
7. Hoa isn't as good at English as Lan.
8. The water wasn't warm enough for the children to swim in.
9. You don't have to set off early.
10. He'd rather go out for a meal than have dinner at home.

IV.

1.unhappily

2.childhood

3.excited

4.succesfully

5.competitors

6.flights

7.entertainment

8.behaviors

9.proud

10.uncomfortable

V.

1.A: said->saying

2.B: rung->rang

3.A: It not difficult->It is not difficult

4.B: how explain->how to explain

5.B: greatly->great

6.B: take->took

7.B: since->from

8.B: believe->believed

9.D: does Jane->did Jane

10.B: doing->to do

VI.

1.Unless the weather is bad , we will go away

6.The date of the meeting will have to be changed again

7.Hoa isn't as good at English as Lan

8.The water wasn't warm enough for the children to swim in

9.You don't need to set off early