-54的相反数是54,它的倒数是-45,它的绝对值是54.
He has only _______ friends , so he often plays by himself. [ ]
A. a few
B. few
C. a little
D. little
在实验结束后要处理资料时若缺乏人们会不知需用哪种统计分析方法
A.实验条件B.实验资料C.实验设计方案D.实验手段E.实验经验