题目

71. attach→ n __________________                     72. persuade→adj_________________ 73.remain→adj _________________                      74. popular → v__________________ 75. reason→adv_________________                     76. pure→ v _____________________ 77.criticise→n__________________                       78. mercy→adj____________________ 79. fog→ adj___________________                       80. responsible→opp_______________已知函数y=ax2-3x+3（a＞0，a≠1）在[0，2]上有最小值8，则a等于（　　） A、2B、16C、2或16D、4