天然气有哪些用途？

已知a，b，c∈R，函数f（x）=ax²+bx+c，g（x）=ax+b，当-1≤x≤1时，|f（x）|≤1，

求证：①|c|≤1．

②当-1≤x≤1时，|g（x）|≤2．

流行病学中属描述性研究的是（）。

A.现况调查

B.病例对照研究

C.队列研究

D.临床试验

E.社区试验

（6分）2013年11月19日至12日，中 * * 党第十八届中央委员会第三次全体会议在北京举行。某校团委积极行动，开展了一系列的主题教育实践活动，请你参与并完成下列任务。

（1）在学校举行的征文中，某学生这样写道：在实现伟大中国梦的征程中，我们要始终坚持以经济建设为中心，把四项基本原则作为我国的兴国之要，以改革开放作为我国发展的政治保障，以更大的勇气，更高超的智慧，劈波斩浪，创造新的辉煌。

该学生的文章中有两处知识性错误，请加以改正。（4分）

            改为           ；②            改为          

（2）中共十八届三中全会勾勒未来10年的中国改革蓝图。该校某班学生寄语十八届三中全会，纷纷写下自己的改革梦想。请你从政治改革、经济改革、户籍制度、社保就业、收入分配、房价物价、教育医疗、 * * 倡廉、环境保护、其他等方面选择一项写出你的改革梦想。（2分）

我的改革梦想：                                                                                                                                                               

A few years ago I had an "aha!" moment regarding handwriting.

I had in my hand a sheet of paper with handwritten instructions on it for some sort of editorial task. It occurred at first that I did not recognize the handwriting, and then I realized whose it must be. I finally became aware of the fact that I had been working with this colleague for at least a year, maybe two, and yet I did not recognize her handwriting at that point.

It was a very important event in the computerization of life—a sign that the informal. Friendly communication of people working together in an office had changed from notes in pen to instant messages and emails. There was a time when our workdays were filled with little letters, and we recognized one another’s handwriting the way we knew voices or faces.

As a child visiting my father’s office, I was pleased to recognize, in little notes on the desks of his staff, the same handwriting I would see at home in the notes he would leave on the fridge—except that those notes were signed "dad" instead of "RFW".

All this has been on my mind because of the talk about The Rise and Fall of Handwriting, a book by Florey. Sire shows in her book a deep concern about the fall of handwriting and the failure of schools to teach children to write well, but many others argue that people in a digital age can’t be expected to learn to hold a pen.

I don’t buy it. I don’t want to see anyone cut off from the expressive, personal associations that a pen still promotes better than a digital keyboard does. For many a biographer, part of really getting to know their subjects is learning to read their handwriting.

What some people advocate is teaching one of the many attractive handwritings based on the handwriting of 16th century Italy. That may sound impossibly grand—as if they want kids to learn to draw by copying classical paintings. However, they have worked in many school systems.

According to the author, handwritten notes ().

A．are harder to teach in schools

B．attract more attention

C．are used only between friends

D．carry more message

mdb”数据库中有单位信息、职位信息、职位申请和个人信息四张表。
(1)以职位信息表和单位信息表为数据源，创建查询“查询1”，查询要求中有“工作经验”的职位信息。结果显示职位编号、职位名称、要求和单位名称。查询结果如图所示。

(2)以单位信息、职位信息、职位申请和个人信息四张表为数据源，创建参数查询“查询2”，实现输入帐号显示职位申请信息。参数提示为“请输入帐号”，结果显示帐号、姓名、职位编号和单位名称字段。查询结果如图所示。