50. A. pollute         B. university         C. reduce                  D. confuse
61. A. potatoes          B. goes                   C. tomatoes          D. diseases
62. A. used               B. designed             C. wanted            D. cried
63. A. plays             B. doors                  C. beds                D. students
64. A. easily             B. ready                  C. teacher             D. speaker
65. A. fly                 B. hobby                 C. energy              D. ordinary
66. A. dump             B. bluff                    C. nuclear            D. plumber
67. A. garbage         B. garage                 C. sewage            D. carriage
68. A. pagoda          B. category               C. suggest           D. regular
69 A. plumber         B. bath                     C. label                D. garbage
70. A. beach           B. clean                  C. instead              D. leave
71. A. played        B. filled                  C. died                    D. walked
72. A. watch          B. Christmas          C. chat                   D. exchange
73. A. equal            B. fashion           C. champagne            D. match
74. A. economy      B. occasion         C. freedom                 D. logical
75. A. invite           B. river                C. shrine                     D. primary
76. A. encourage    B. proud              C. enough                   D. young
77. A. cross                     B. conclude             C. carry                        D. celebrate
78. A. dripped                 B. conserved           C. received                    D. learned