ответ:

exercise 2:

1. haven't visited

2. hasn't flown

3. have traveled

4. have eaten

5. have made

6. hasn't bought

Exercise 3:

1. how

2. ever

3. never

4. for

5. since

6. just

7. yet, already

Exercise 4:

1. how long have you lived here?

2. they have celebrated this day for hundred of years

3. I haven't seen them since last Tuesday

4. we have just seen the firework display

5. I have never eaten pancakes

6. have you ever heard reggae music?

7. has he finished that book yet?

8. I have already made some baked potatoes to eat