题目

It is said that in Australia there is more land than the government knows _____.      A. it what to do with    B. what to do it with        C. what to do with it        D. to do what with it 答案：C（2012•鹰潭模拟）已知数列{an}的通项公式是an=-n2+12n-32，其前n项和是Sn，对任意的m，n∈N*且m＜n，则Sn-Sm的最大值是1010．