Ex1:Choose the word whose primary stress is different from the others.
16. A. kangaroo B. employee C. popular D. preparation
17. A. national B. medical C. historical D. chemical
18. A. traffic B. agree C. noisy D. student
19. A. listen B. visit C. borrow D. obey
20. A. Chinese B. Japanese C. historic D. biology
21. A.creativity B.immature C.negative D.nationality
22. A.impossible B.importantly C.stability D.connectivity
23. A.unlimited B.illogical C.conservation D.priority
24. A.opportunity B.competitive C.communicative D.unfortunate
25. A.authority B.impolite C.unhealthy D.repetitive