【简答题】已知 是递增的等差数列,满足 (1)求数列 的通项公式和前n项和公式; (2)设数列 对 均有 …+ 成立,求数列 的通项公式.
【单选题】To my _____, I lost touch with my best friend.
【判断题】平行度是指两平面或者两直线平行的误差最小允许值。
【简答题】根据汉语提示完成下列句子。 1. I don't keep in touch with her, because I lost her ______ ______ (电话号码). 2. The young lady receives a ______ ______(金戒指) from a rich man on Valentine's Day (情人节). 3. ______ ______ (打扰...
【简答题】下列函数在指定过程中为无穷小量的是( )A. B. C.
【单选题】Guess what! I came across my primary school science teacher this morning, ______ I have lost touch for almost 20 years.