题目

____killing of so many protected animals made____stir among the local people in Africa.  A.不填;不填            B.The;不填               C. 不填;a             D.The;a   答案：D已知等差数列{an}中,a3=a9,公差d＜0,则使前n项和Sn取得最大值的正整数n的值是(    )A.4或5               B.6              C.6或7             D.8或9