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17. You can sleep in this sleeping________  during the trip.

     A. tube                             B. pack                        C. bag                          D. coat

18. Students________ in an exam or the teacher will send them out.

     A. must cheat                   B.mustn’t to cheat      C. mustn’t cheat         D. must to cheat

19. Is Vung Tau Beach_______than Long Son Beach?

     A. more crowded            B. crowdeder              C. crowded more        D. much crowded

20. Visitors________ photos in their area without their permission.

     A. mustn’t to take           B. must to take            C. must take                D.mustn't take