15. Jane advised David to take a holiday.
16. She warned him not to repair the computer himself.
17. Helen offered me to bring the sandwiches to the party.
18. If she had said Hello, he wouldn't have been upset.
19. If I were a millionare, I could afford to buy the luxurious car.
20. If you don't speak Vietnamese quickly, foreigners won't understand you.
21. If he prepared his map carefully, he wouldn't get lost.
22. If he doesn't answer her immediately, she won't get any information
23. If my bike hadn't broken down, I wouldn't have stopped my study.
P/s: Em làm mấy câu chưa làm thôi ạ, mấy câu trên đúng rồi :v
