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问题 选择题

下列关于电磁波的说法正确的是（　　）

A．电磁波是一种纵波

B．可见光是电磁波

C．电磁波不能产生干涉和衍射现象

D．电磁波必须依赖介质传播

答案

A、电磁波的传播方向与振动方向相互垂直，故电磁波是横波，故A错误．

B、可见光是电磁波的一种，故B正确．

C、电磁波能产生干涉和衍射现象．故C错误．

D、电磁波的传播不需要介质．故D错误．

故选B．

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4的平方根为______，
64
的立方根为______．
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完形填空

仔细阅读下面的短文，短文中有10个空格。请根据语境或按照括号内的具体要求完成语法填空。

Soon after Dave left college, one of his uncles, who was rich and had no    小题1:   of his own, died and left Dave a lot of money, so he decided to   小题2:   (动词) his own real estate agency(房地产公司).

He found a nice office,    小题3:   (buy) some new furniture and moved in. He had only been there for a few hours when he heard someone coming    小题4:   the door of his office.

“It’s my first customer!” he thought. He quickly picked up    小题5:   (冠词) telephone and pretended to be very busy    小题6:   an important call from someone in New York   小题7:   wanted to buy a big and expensive house in the country.

The man knocked at the door    小题8:  this was going on, came in and waited   小题9:   (polite) for the agent to finish his conversation. Then he said to him, “I’m from the telephone company, and I   小题10:   (send) here to connect your telephone.”
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