I. Choose the words whose underlined part is pronounced differently from that of the others in each group. 16. A. cough B. laugh C. enough D. high 17. A. collect B. clean C. city D. cracker 18. A. pottery B. melody C. modal D. profit 19. A. near B. clear C. dear D. learn 20. A. knocked B. needed C. founded D. wanted 21. A. played B. travelled C. planned D. watched 22. A. buffalo B. unhappy C. pollution D. structure 23. A. collection B. comic C. concert D. volunteer 24. A. bread B. really C. head D. death 25. A. walked B. crowded C. needed D. excited 26. A. early B. beat C. realize D. reader 27. A. holiday B. lazy C. take D. vacation 28. A. coop B. door C. food D. boot 29. A. nervous B. scout C. household D. mouse 30. A. safety B. tasty C. pancake D. nature