问题 填空题

数列{an}的前n项和为Sn=n2+1(n∈N*),则它的通项公式是(    )。

答案

写作题
你收到美国笔友Sally 来信后,请你给她写封回信介绍一下你的家庭成员及你们的饮食习惯。40 词左右。
MealsFatherMotherLiu Mei
BreakfastEggs, apples, bread Eggs and bananasEggs and strawberries
Lunch   Noodles with tomatoes and eggsNoodles with tomatoes and eggsHamburgers  and pears
DinnerPorridge, saladPorridge and saladPorridge and salad
DessertFrench friesIce cream
Dear Sally ,
       Thank you for your letter.                                                                                                                
                                                                                                                                                                
                                                                                                                                     Yours,
                                                                                                                                      Liu Mei.
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