单项选择题
2.1,3.2,4.3,5.4,( )A.4.5B.6.5C.3.5D.5.6
单项选择题2.1,3.2,4.3,5.4,( )
1,-1/2,1/3,-1/4,1/5,( )A.-1/6B.1/8C.1/7D.1/6
单项选择题1,-1/2,1/3,-1/4,1/5,( )
3/2,5/4,7/6,9/8,11/10,( )A.13/12B.12/11C.14/13D.15/14
单项选择题3/2,5/4,7/6,9/8,11/10,( )