等差数列{an}前n项和Sn,a1=2,S10=110,若 ,则数列{bn}的前n项和为____.
–Are you free tonight?
—Sorry, but I'm not . I've got so much homework to do.
①掌握基本的交往礼仪和技能 ②了解社会公共生活的共同准则
③养成文明礼貌、遵纪守法的好习惯 ④与身边所有的人坦诚相待