A:对任意实数x,都有x2﹣2x+1<0
B:对任意实数x,都有x2﹣2x+1≤0
C:存在实数x,有x2﹣2x+1<0
D:存在实数x,有x2﹣2x+1≤0
—I'm thirsty.I want some water. —OK, let's go to the shop now.
选项
A
B
C
D
物质
Fe(铁丝)
S(硫粉)
C(木炭)
H2(氢气)
在足量氧气中燃烧的产物
氧化铁
(Fe2O3)
二氧化硫
(SO2)
一氧化碳
(CO)
过氧化氢
(H2O2)
已知数列{an}是无穷等比数列,其前n项和是Sn,若a2+a3=2,a3+a4=1,则limn→∞Sn的值为____ .
I like fruit as well as vegetables, because they are both good for my health.