A:赤道
B:北回归线
C:南回归线
D:北极圈
Although many Americans move a lot, they still________and understand each other's dialects.
(Ⅰ)求证:数列{log2(an+1)}为等比数列:
(Ⅱ)设bn=n1og2(an+1),数列{bn}的前n项和为Sn,求证:1≤Sn<4.
不同的区域间存在( )
根据汉语意思完成句子