我国发射人造卫星用的长征3号运载火箭的第三级里装有液体状态的氧和氢．要把氧和氢液

发布时间：2017-06-02 06:30 │ 来源：www.tikuol.com

题型：选择题

问题：

我国发射人造卫星用的长征3号运载火箭的第三级里装有液体状态的氧和氢．要把氧和氢液化后再装进火箭的主要原因是（　　）

A．火箭头与大气摩擦升温，液氧和液氢气化能吸收大量的热，给火箭头降温

B．大气层外温度很低，液氧和液氢凝固能放出大量的热，使卫星保持温度恒定

C．氧和氢液化后体积缩小，便于贮存和运输

D．氧和氢液化后质量增大，能增大火箭的运载能力

考点：熔化的规律及其特点汽化及汽化的特点

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阅读理解。

      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

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患者，女性，36岁。间断右下腹痛6个月，伴腹泻、发热，体温多波动于37～38℃。否认结核病史和肺结核密切接触史。查体右下腹可触及包块，可移动，有压痛，无反跳痛

为明确诊断最重要的检查是（）.

A.肿瘤指标

B.便找结核杆菌

C.腹平片

D.结肠镜检查加活检

E.胸片

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严复是清朝的[ ]

A．实业家

B．教育家

C．启蒙思想家

D．诗人

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Airbridge中，对于SET RFMTDO命令，说法正确的有（）。

A.该命令用于启动和停止EVDO系统的RFMT跟踪

B.指定IMSI号的呼叫跟踪"可输入的最长的跟踪时限为36小时

C.启动一次新的RFMT跟踪任务前，必须把对应跟踪的文件保存目录清空

D.指定IMSI号的呼叫跟踪"可以多次启动，最大可跟踪的指定IMSI为10个

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机器能做功或实现能量转换，机构则不能。

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