关系数据库是 (32) 的集合，它由一个或多个关系模式定义。A．元组 B．列 C．字

[1] At some point in your life you are bound to be required to give a speech. But are you capable of having the effect on an audience that you want to have? Here are some things to keep in mind.     

[2] You may think it's good to create an informal effect, or even that it' s cool to use filler words (填充词) such as “like” and “you know”. But in reality, these words add nothing, and create the danger of making you sound foolish and uninformed.

[3] Pauses can be of significant help in adding depth to your speech, but only when they  are used at the right moments. Pausing suddenly and with a panicked look will just make your audience uneasy. Also, a very long silence is the last thing you need. Make sure that your pauses are nicely placed if you want to sound like a speaker who has absolute control of what he is talking about.

[4] You also need to be careful when you switch to a new idea during the course of a speech. Often speakers ________such as “well”, “so”, and so on, when they move on to new ideas. My advice, however, is to avoid such words and to try to think of a way of making a tradition that is unique to the topic of your speech.

[5] Finally, avoid “umming” and “ahhing” he way many people do when they give speeches. You want to sound confident and assured, and the way not to do so is to put an “urn” or an “ah” in the middle of every sentence.

小题1:What is the text mainly about? (No more than 8 words)

_________________________________________________________________________

小题2:Complete the following statement with proper words. (No more than 3 words)

It's careful to switch to ________________________ when you give a speech.

小题3:Fill in the blank in Paragraph 4 with proper words. (No more than 5 words)

__________________________________________________________________________

小题4:Why does the author say it' s not good to use filler words? (No more than 12 words)

_______________________________________________________________________

小题5:What does the word "they" (paragraph 3) probably refer to? (No more than 2 words)

_________________________________________________________________________

小丹同学在学习酸的性质时，从同一卷镁带中剪取相等的两根镁带，分别与室温下H⁺浓度相同的稀盐酸、稀硫酸反应。观察发现：镁带在稀盐酸中放出气泡的速率明显快于在稀硫酸中放出气泡的速率。

【查阅资料】

1、金属与酸发生置换反应，其本质是金属单质与H⁺反应。

2、生产H₂速率主要取决于：①金属的表面积 ②溶液中H⁺浓度 ③温度等条件。

3、H⁺的浓度与1L溶液中H⁺数目成正比。

4、溶液中除H⁺外的其它离子可能会影响反应速率。

【提出问题】

①小丹同学在进行上述实验时，控制了镁带与酸反应的哪几个条件？（回答两条即可）

②上述反应中Cl^-、SO₄^2-如何影响反应速率？

【猜想假设】

Ⅰ、 Cl^-促进了镁与酸的反应，SO₄^2-对反应无影响。

Ⅱ、 SO₄^2-抑制了镁与酸的反应，Cl^-对反应无影响。

Ⅲ、                                         。

请回答问题①，完成猜想Ⅲ。

【实验探究】为了证明猜想，小丹设计了如下实验：

实验编号	铝片长度	H+浓度相同的酸	反应片刻后添加少量试剂	产生气泡的速率	结论
A	2cm	5 mL	Na2SO4固体	无明显变化	（结论A）
B	2cm	5 mL	（试剂B）	明显加快	Cl-对反应有促进作用

试剂B是       （化学式）固体。

【结论】结论A为                                            。

【反思】将试剂B改用HCl气体，不能达到实验目的，其原因是         。

85乘32与23的和，积是多少？列式是85×32+23．______．

举办农运会的意义有（）

A.充分体现党和国家高度关心农业、关注农村、关爱农民

B.也是党中央、国务院贯彻落实‚以人为本‛的思想，提高广大农民的体育健康意识，展现农民的精神风貌

C.全面展示新时代中国富裕了的农民追求美好生活的良好愿望和拼搏进取的新形象。

D.通过加强农民体育健身，引导农民有更旺盛的精力投入生产建设，不断提高生活水平，创造美好未来

各省（市）石油分公司设数据库系统安全管理员一名，其任职由各省（市）石油分公司加油卡系统运行维护管理部门批准。