若数列{an}是等差数列，首项a1＞0，a2003+a2004＞0，a2003．a2004＜0，则使前n项和Sn＞0成立的最大自然数n是_刷题宝

题干

若数列{a_n}是等差数列，首项a₁＞0，a₂₀₀₃+a₂₀₀₄＞0，a₂₀₀₃．a₂₀₀₄＜0，则使前n项和S_n＞0成立的最大自然数n是（）

A：4005

B：4006

C：4007

D：4008

上一题下一题 0.0难度选择题更新时间:2016-12-09 08:07:26

答案(点此获取答案解析）

B

同类题1

According to a UN report, one third of the world population have no ____ to clean drinking water and health care．

同类题2

电石（主要成分为CaC₂，杂质为Ca₃P₂及CaS等）是重要的基本化工原料，主要用于生产乙炔气．

（1）为探究碳化钙合成机理，有学者认为可能存在以下5种反应（状态已省略）：

①CaO+3C⇌CaC₂+CO平衡常数K₁

②CaO+C⇌Ca+CO平衡常数K₂

③Ca+2C⇌CaC₂平衡常数K₃

④2CaO+CaC₂⇌3Ca+2CO平衡常数K₄

⑤CaC₂⇌Ca+2C平衡常数K₅

相应图象如下：

同类题3

的一条切线l与直线

垂直，则l的

方程为（）

同类题4

以下关于学习的认识，你认为不正确的是（）

同类题5

阅读下列短文, 从每题所给的四个选项(A、B、C、D)中选出最佳选项。

Film Reviews(影评)
James	I really enjoyed this movie．It's a fun movie for the whole family．I had really good laughs and enjoyed being there
Sam	I would recommend this movie to everyone．In fact, when you go to see it together with your family or friends, I think this movie has something you will really enjoy!
John	I have seen some movies of this kind, but this one is the best．It is so well made．Some of the scenes are so beautiful．
Mary	I went to see this movie with my nine-year-old daughter this Tuesday．I really didn't know too much about it before．My daughter and I were surprised at how funny it was．Just couldn't help laughing．I would recommend this movie to the whole family .

小学学科试题库

初中学科试题库

高中学科试题库