当你下午在街上遇到朋友时,可以这样和他打招呼: ( )
A:Good morning!
B:I'm fine.
C:How are you?
① S=12+14+18+⋯+12100
② S=12+14+18+⋯+12100+⋯
③ S=12+14+18+⋯+12n (n≥1且n∈N*)