能准确反映个体儿童发育水平的是
A．年增加百分位数B．曲线图法C．指数法D．标准差分法E．等级评价法
参考答案：E
等差数列{an}满足3a4=7a7，且a1＞0，当前n项和Sn最大时，n=______．
Many students is not sure what to_______ at the university;they can’t make up their
mind about their future.
A．take up
B．make up
C．pick up
D．build up
