已知等差数列{an}的前n项和胃Sn,公差d≠0,且S3+S5=50,a1,a4

题型:解答题

问题:

已知等差数列{an}的前n项和胃Sn,公差d≠0,且S3+S5=50,a1,a4,a13成等比数列.

(1)求数列{an}的通项公式;

(2)若从数列{an}中依次取出第2项、第4项、第8项,…,第2n项,…,按原来顺序组成一个新数列{bn},记该数列的前n项和为Tn,求Tn的表达式.

考点:等比数列的定义及性质数列求和的其他方法(倒序相加,错位相减,裂项相加等)
题型:解答题

阅读理解。

    People all over the world cat rice.Millions of people in Asia  Africa and South America eat it every day of their lives. Some people eat almost nothing but rice.

     Rice is a kind of grass. There are more than 7, 000 kinds of rice. Farmers grow rice in many countries, even in the South part of the United States think that is started to grow in two places. They think that one

kind of rice grew in Southern Asia thousands of years ago. Someone in China wrote about it almost 5, 000 years ago. Another kind probably grew in West Africa. Other scientists think that rice came from India,

arid Indian travelers took it to other parts of the world.

     These are two main ways to grow rice. Most rice grow in wet soil. People in many countries do all of

the work of growing rice by hand. This is the same way farmers worked hundreds of years ago. In some

countries,  people now use machines on their rice farms.

    People use every part of the rice plant. They make animal feed and rice oil from it. They also make

baskets,  brooms and roofs for their houses. They burn dry rice plants in fires for cooking.

根据短文内容,回答下列问题。

1. How many kinds of rice came from?

__________________________________________

2. Where do scientists think rice came from?

__________________________________________

3. How did farmers grow rice hundreds of years ago?

__________________________________________

4. Which part of the rice plant can be used!

__________________________________________

5. What do you think is the best way to grow rice?

__________________________________________

题型:解答题

认证机构对申请单位的质量管理体系审核是认证的关键环节,其基本工作有( )。

A.认证申请的审查与批准

B.文件审核

C.现场审核

D.审批与注册发证

E.提出审核报告

题型:解答题

先兆子痫产妇产后出血不能使用 ()

A.麦角新碱肌内注射

B.缩宫素静脉滴注

C.垂体后叶素静脉滴注

D.吗啡

E.硫酸镁

题型:解答题

社会工作者老康为中年丧偶妇女群体开展心理疏导,一段时间后,老康希望借助实验研究的方法来检验服务效果,她最适宜选择的实验设计是()

A.单后测控制组设计

B.索罗门四组设计

C.前后测控制组设计

D.简单时间序列设计

题型:解答题

以下说法中正确的是(  )

A.物体的机械能和物体的内能是同种形式的能,都与物体的机械运动和分子热运动以及分子间的相互作用情况有关

B.单位质量的某种物质温度升高1℃吸收的热量与它温度降低1℃放出的热量相等

C.通过直接感知的现象,推测无法直接感知的事实,这是物理学中常用的方法.例如通过扩散现象认识到分子间存在斥力

D.高温的铁水具有内能,低温的冰块没有内能

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