问题 选择题

下列用来分析生活、生产中化学知识的问题,正确的是

A.市场上有“葡萄糖酸锌”、“加碘食盐”等商品,这里的碘、锌是指元素

B.用一种高效的催化剂可把水变成汽油

C.蚊虫叮咬后,会在人的皮肤内分泌蚁酸使皮肤肿痛,可涂点醋酸来减轻痛痒

D.消防队员向着火的房子喷水,是通过隔绝可燃物与空气接触,达到灭火目的

答案

A

水中没有碳元素,所以根据质量守恒定律,反应前后元素的种类是不变的,所以水是不可能变成汽油的,故B错误,

蚊虫叮咬后分泌的是酸性物质,所以应该涂上碱性物质,故C错误,

用水灭火是利用降低可燃物的温度到着火点一下来灭火的,故D错误。

阅读理解

阅读短文,选择正确答案。

    We are all called upon to make a speech at some point in life, but most of us don't do a very good job. This

article gives some suggestions on how to give an effective speech.

    So, you have to give a speech and you're terrified. You get nervous, you forget what you want to say, you

stumble over words, you talk too long, and you bore your audience. Later you think, "Thank goodness, it's

over. I'm just no good at public speaking. I hope I never have to do that again." 

    Cheer up! It doesn't have to be that bad. Here are some simple steps to take the pain out of speech making.

Ask yourself the purpose of your speech. What is the occasion? Why are you speaking? Then, gather as many

facts as you can on your subject. Spend plenty of time doing your research. Then spend plenty of time

organizing your material so that your speech is clear and easy to follow. Use as many examples as possible, and

use pictures, charts, and graphs if they will help you make your points more clearly. Never forget your audience.

Don't talk over their heads, and don't talk down to them. Treat your audience with respect. They will appreciate

your thoughtfulness. 

    Just remember: be prepared. Know your subject, your audience, and the occasion. Be brief. Say what you

have to say and then stop. And be yourself. Let your personality come through so that you make

person-to-person contact with your audience. If you follow these simple steps, you'll see that you don't have to

be afraid of public speaking. In fact, you may find the experience so enjoyable that you volunteer to make more

speeches! You're not convinced yet? Give it a try and see what happens.

1. The main idea of this article is _______. [ ]

A. you can improve your speaking ability   

B. a poor speaker can never change   

C. always make a short speech   

D. it is hard to make a speech

2. Paragraph 2 implies that _______. [ ]

A. many people are afraid of giving a speech   

B. many people are happy to give a speech   

C. many people do not prepare for a speech   

D. many people talk too long

3. The phrase "talk over their heads" means ________. [ ]

A. speak too loudly   

B. look at the ceiling   

C. look down upon them   

D. use words and ideas that are too difficult

4. All of the following statements are true except that _______. [ ]

A. few people know how to make good speeches   

B. a lecturer does not need to organize his speech   

C. research is important in preparing a speech   

D. there are simple steps you can take to improve your speaking ability

5. The title for this passage may be _______. [ ]

A. Do Not Make a Long Speech   

B. How to Give a Good Speech   

C. How to Prepare for a Speech   

D. Try to Enjoy a Speech

单项选择题