Exercise 2:
1. play → playing
2. study → studying
3. do → doing
4. went → go
5. sleep → sleeping
6. have → had
7. broke → break
8. go → went
9. am → was
10. turn → turned
Exercise 3(1):
1. was walking
2. was attending
3. was understanding
4. was riding
5. were living
6. was walking
7. was going
8. was studying ... were having
9. were dancing
10. were sitting
Exercise 3(2):
1. jogs
2. is watching
3. doesn't go
4. is skipping
5. isn't
6. speak
7. will visit
8. will go
9. wears ... is wearing
10. isn't raining ... shines
11. goes
12. have you stay
13. is falling
Chúc em học tốt. Xin 5 sao và CTLHN.