题干

如图所示,将甲手机挂在玻璃罩内,用乙手机拨打甲手机,能听到甲手机响亮的振铃声,同时也能看见甲手机来电指示灯闪烁。如果用抽气机不断地抽取玻璃罩内的空气,再用乙手机拨打甲手机,听到甲手机的振铃声越来越小,最后几乎听不到振铃声,但仍能看见甲手机来电指示灯闪烁。这个实验说明(  )

A:声音和光的传播都需要介质

B:声音和光都可以在真空中传播

C:声音可以在真空中传播而光不能

D:光可以在真空中传播而声音不能

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答案(点此获取答案解析)

D

同类题2

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。

    The Internet has opened up a whole new online world for us to meet, chat and go where we've never been before. But just as in face to face communication, there are some rules of behavior that should be followed when on line.

    ____ Imagine how you'd feel if you were in the other person's shoes. For anything you're about to send,ask yourself, "Would I say this to the person's face?" If the answer is no, rewrite and reread.____

     If someone in the chat room is rude to you, your instinct (本能) is to fire back in the same manner. But try not to do so. ____ If it was caused by a disagreement with another member, try to fix the situation by politely discussing it. Remember to respect the beliefs and opinions of others in the chat room.

    ____ Offer advice when asked by newcomers, as they may not be sure what to do or how to communicate. When someone makes a mistake, whether it's a stupid question or an unnecessarily long answer, be kind about it. If it's a small mistake, you may not need to say anything. Even if you feel strongly about it, think twice before saying anything. Having good manners yourself doesn't give you license to correct everyone else. ____ At the same time, if you find you are wrong, be sure to correct yourself and apologize to those that you have offended. It is not polite to ask others personal questions such as their age, sex and marital status. Unless you know the person very well, and you are both comfortable with sharing personal information, don't ask such questions.

A. It's natural that there're some people who speak rudely or make mistakes online.

B. Repeat the process till you feel sure that you'd feel comfortable saying the words to the person's face.

C. Everyone was new to the network once.

D. The basic rule is simple: treat others in the same way you would want to be treated.

E. When you send short messages to a person online, you must say something beautiful to hear.

F. You should either ignore the person, or use your chat software to block their messages.

G. If you do decide to tell someone about a mistake, point it out politely.