【单选题】如图,已知正△A 1 B 1 C 1 的边长是1,面积是P 1 ,取△A 1 B 1 C 1 各边的中点A 2 ,B 2 ,C 2 ,△A 2 B 2 C 2 的面积为P 2 ,再取△A 2 B 2 C 2 各边的中点A 3 ,B 3 ,C 3 ,△A 3 B 3 C 3 的面积为P 3 ,依此类推.记S n =P 1 +P 2 +…+P n ,则 lim n→∞ S n ( )
【简答题】Please fill in the blanks with what you hear. There are no more than 2 words for each blank. 1. One study found that just seeing advertisements from one to three minutes can have a __________ on girls...