Question

Turn on the radio. A program will come out from a broadcasting station miles and miles away. We know that sounds and music themselves couldn’t travel that distance through space .There must be something that brings the program from the station. But what is this silent carrier ( 载体) ?

This is known as radio waves. However, we can’t see them or even hear them. In fact, nobody knows exactly what they are. Nevertheless( 然而) ，we know that  they are made by electricity .

At the broadcasting station, people talk, sing, play musical instruments or make many other sounds. These sounds are changed into electricity. Then from the broadcasting aerial (天线)of a tall tower , electricity sends out radio waves which travel  in all directions .And some of them reach your radio aerial. What happens next is a magical thing. The radio waves start an electric current ( 电流) in your aerial like the one that was first made in the broadcasting station . Finally, the loudspeaker in your radio set changes the electricity into sound .Therefore, you hear the program.

根据材料内容选择最佳答案，将其标号填入题前括号内。

1.When you turn on the radio _________________.

A. you can see a program

B. you can hear a program

C. a picture will appear

D. you can feel the electric current.

2.The silent carrier that brings the program to you is called ____________.

A. radio set    B. sound waves

C. radio waves D. radio current

3.Electricity sends out radios waves from _________________.

A. the broadcasting aerial of a tall tower.

B. you radio set

C. all directions

D. a broadcasting station

4.The electricity is changed into sound by _______________.

A. the radio waves                B. the aerial

C. the radio program              D. the loudspeaker

5.You may find this passage in a ______________.

A. guidebook

B. science magazine

C. fashion newspaper

D. fictional novel

Answer

1.B

2.C

3.A

4.D

5.B

【解析】

试题分析：打开收音机，节目会从几公里外的广播站传来。传播节目的载体是无线电波。在广播站人们的声音转换成电流，通过高塔的天线传送无线电波，最后收音机里的扬声器将电流转换为声音。

1.细节理解题。根据第一段第一、二句可知，打开收音机，节目会从几公里外的广播站传来。故选B。

2.细节理解题。根据第一段最后一句和第二段第一句可以得知，传播节目的载体是无线电波。故选C。

3.细节理解题。根据文章第三段第三句可知，电流通过高塔的天线传送无线电波。故选A。

4.细节理解题。通过最后一段倒数第二句可以得知，最后收音机里的扬声器将电流转换为声音。故选D.

5.主旨推断题。这是一篇科技文章，所以可以在科技杂志看到。故选B。

考点：科技类阅读。