Ex3: 
1. went
2. moved
3. bought
4. didn't take 
5. weren't
6. was
7. Where did you go...?
8. Did they help...?
9. watched/ didn't like
Ex4:
1. was preparing      7. was playng
2. were playing        8. was watching
3. was practising      9. was doing
5. weren't cycling
6. were sitting    
Ex 5: 
1.has been/since
2. has worked/for
3.has been/for

4. have sent/ since
6. hasn't eaten/since
7. have been/ since
8. have lived/ for
9. has gone/ since
Ex6:
1. plays
2. doesn't sleep 
3.Do you like...?
4. aren't watching
5. has just opened
6. hasn't bought/ sold
7. installed 
8. has been/ came
9. is
10. Where does she buy...?
11. is falling
12. waters
13. weren't listening/came
14. rises/sets
15. is playing

=>
3/
1. went
2. moved
3. bought
4. didn't take
5. weren't
6. was
7. Where were you
8. Did they help
9. watched/didn't like

4/
1. was preparing
2. were playing
3. was practising
4. were not cycling
5. were you doing
6. were sitting
7. were playing
8. was watching
9. was doing

5/
1. has been/since
2. has worked/for
3. has been/for
4. have sent/since
5. hasn't eat/for
6. have been/since
7. have lived/for
8. has gone/since

6/
1. plays
2. doesn't sleep
3. Do you like
4. are not watching
5. has just opened
6. has not bought/sold
7. installed
8. has been/came
9. is
10. does she buy
11. is falling
12. watered
13. was not listening/came
14. rises/sets
15. was playing