问题 选择题

下列化学用语正确的是(  )

A.氟化氢的电子式:

B.氯原子的结构示意图:

C.氯化钠的电离方程式:NaCl=Na++Cl-

D.乙醇的结构式:C2H6O

答案

A.共价化合物电子式的书写是用.或x标出每个原子的最外层电子数以及原子间的共用电子对,使每个原子达到稳定结构,离子化合物电子式的书写是阴离子和复杂阳离子用[]括起来,在右上角标出电荷和电性,HF是共价化合物,不能写成离子化合物的形式,故A错误;

B.由图示可知:核电荷数=质子数=17<核外电子数=18,为阴离子,故B错误;

C.氯化钠能完全电离出钠离子和氯离子,故C正确;

D.乙醇的结构式为:CH3CH2OH,故D错误.

故选C.

阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

     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.    1   .

     So, you have to give a speech-and you are terrified. You get nervous, you forget what you want to

say, you stumble (结结巴巴) over words, you talk too long, and you bore your audience. Later you think,

"Thank Goodness, it's over. I'm just not good at public speaking. I hope I never have to do that again."

     Cheep up!    2   . 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 your time doing your research. Then spend plenty of your 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 help you make your points more clearly.     3   . 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.    4   . 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 will 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?    5   .

A. It doesn't have to be that bad.

B. Take several deep breaths before your speech.

C. This article gives some advice on how to give a good speech.

D. Say what you have to say and then stop.

E. Don't say what you aren't familiar with.

F. Never forget your audience.

G. Give it a try and see what happens.

判断题