题干

如图示,小聪到银滩游玩时看到有一种沙滩车能在松软的沙滩上自由飞驰,非常好玩,小聪走近沙滩车时发现沙滩车的车轮做得比普通车的车轮宽很多,车轮上的花纹也粗很多.请你用所学知识解释为什么沙滩车的车轮做得比较宽和花纹比较粗.

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答:沙滩车的车轮做得比较宽,是在压力一定时,增大受力面积来减小车对沙滩的压强,从而使车不易陷进沙里面;

车轮的花纹比较粗,是在压力一定时,通过增大接触面的粗糙程度,增大车轮与沙滩间的摩擦力,使车轮不易打滑.

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阅读理解

    People can't see you when you're speaking on the phone,but they can hear you.So,the way you speak is especially important.In fact,researchers have calculated that 80% of communication over the phone is through your tone of voice; and only 20% is from the words you use.Here are our top tips on how to speak over the phone.

⒈Facial Expressions

    Your facial expression can influence your voice.For example,if you smile,your voice will sound warm and friendly,just the opposite,if you have an angry look on your face,it can make you sound unpleasant.

⒉Volume

    If you speak too loudly,you could sound angry.And if you speak too softly,it'll be difficult to hear you.So,speak loudly enough to be heard clearly,but not so loud that you're shouting.

⒊Pace

    The pace of your voice is how quickly you speak.And this can show how you feel.For example,an angry person might speak faster than normal.Or a downhearted person might speak very slowly.Try speaking a little more slowly than normal.This will make you sound confident,and it'll make it easier for the other person to understand you.

⒋Gestures

    Gesturing can influence the tone of your voice.When you gesture,you bring more air into the lungs,which can make your voice sound warmer.Gestures are also useful to help you stress the right words or even find the words you need.The best thing about gesturing during a phone call is that no one can see what you're doing,so you can gesture as wildly as you like!

⒌Movement

    If you're feeling nervous,stand up and move around.It will reduce the nervousness in your body and help your voice to sound more confident.

⒍Pauses (停顿)

    Using pauses every now and then can help you to slow down.This will make you sound more confident and in control.Also,if you pause after giving some new information,it'll give the other person time to understand it.At the same time,listen to how the other person uses pauses.They could tell you something about the speaker's feeling.For example,when a speaker is really angry,he might use pauses and says,"I…am…so…angry…"