Chọn đáp án đúng: John _____ last week

16. John _____ last week.
A. had his house painted           B. had painted his house
C. had his father to paint            D. had his house paint
17. Today, many serious childhood diseases _____ by early immunization.
A. are preventing                 B. can prevent             C. prevent             D. can be prevented
18. ‘_____ about the eight o’clock flight to Chicago?’ ‘Not yet.’
A. Has been an announcement made             B. Has an announcement made
C. Has an announcement been made             D. Has been made an announcement
19. Do you get your heating _____ every year?
A. checking             B. check                  C. be checked                D. checked

20. All bottles _________ before transportation.         

A. frozen                      B. is frozen                   C. was frozen               D. were frozen