$\text{⇒ Answer:}$

$\text{11. If you don't study harder, you 'll get bad marks.}$

$\text{12. If she was free, she could go out tonight.}$

$\text{13. If I knew something about her background, I would tell you.}$

$\text{14. If I had been hungry, I would have felt like eating.}$

$\text{15. If she weren't shy, she would have many friends.}$

$\text{16. If you had reminded me about Susan's birthday, I would}$

$\text{have remembered.}$

$\text{17. If the car in front hadn't stopped so suddenly, I wouldn't}$

$\text{have crashed into its back.}$

$\text{18. If they hadn't painted the wall brown, the house wouldn't}$

$\text{have looked very dark.}$

$\text{19. If he didn't have to study for his exam, he could go out.}$

$\text{20. If she wasn't lazy, she could pass the exam.}$

$\text{21. If he doesn't pay me tonight, I won't have enough money}$

$\text{ to buy a car.}$

$\text{22. If he didn't smoke too much, he could get rid of his cough.}$

$\text{23. If she wasn't shy, she would enjoy the party.}$

                                    $\text{-----Done by GiaHung2k7-----}$

$\text{Cho mik xin câu trả lời hay nhất, 5 sao + cảm ơn nha.}$

11. If you studied harder, you would get better marks.

12. If she was free, she could go out tonight.

13. If I knew something about her background, I would tell you.

14. If I had been hungry, I would have felt like eating.

15. If she weren't shy, she would have many friends.

16. If you had reminded me about Susan's birthday, I would have remembered.

17. If the car in front hadn't stopped so suddenly, I wouldn't have crashed into its back.

18. If they hadn't painted the wall brown, the house wouldn't have looked very dark. 

19. If he didn't have to study for his exam, he could go out.

20. If she wasn't lazy, she could pass the exam.

21. If he doesn't pay me tonight, I won't have enough money to buy a car.

22. If he didn't smoke too much, he could get rid of his cough.

23. If she wasn't shy, she would enjoy the party.