Question

Light travels at a speed which is about a million times faster than the speed of sound. You can get some idea of this difference by watching the start of a race. If you stand some distance(距离) away from the starter, you can see smoke from his gun before the sound reaches your ears.

This great speed of light produces some strange facts. Sunlight(太阳光) takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light that you can see from it tonight started to travel towards you four years ago at a speed of nearly 2 million km. per minute. In some cases, the light from one of tonight’s stars had started on its journey to you before you were born.

Thus, if we want to be honest, we can’t say, “The stars are shining tonight.” We have to say instead, “The stars look pretty. They were shining four years ago, but their light has only just reached the earth.”

1.Light speed is ______ sound speed.

A. as fast as                          

B. a million times slower than

C. about millions of times faster than     

D. about a million times faster than

2. If you stand 200 meters away from a man who is firing a gun to start a race, you will find out that ______.

A. you can hear the sound before you see the smoke

B. the sound does not travel as fast as light

C. the sound will reach you before the man fires

D. sound travels about a million times faster than light

3.Sunlight obviously(显然的) ______ than the light of the moon.

A. has to travel a greater distance          

B. moves less quickly

C. travels much more quickly            

D. is less powerful

4. The scientific way of saying "The stars are shining tonight" should be ______.

A. the stars have been shining all the time

B. the stars seen tonight will shine four years later

C. the stars were shining long ago but seen tonight

D. the starlight seen today could be seen four years ago

 

Answer 1

【答案】

 

1.D

2.B

3.A

4.C

【解析】

试题分析：这篇短文中作者主要介绍了光的传播速度要远远高于声的传播。文章又向我们描述了一种奇怪的自然现象，引起了人们的思考。

1.细节理解题。根据短文第一句话Light travels at a speed which is about a million times faster than the speed of sound.可知光的传播速度比声音的传播速度要快一百万倍；故选D。

2.细节理解题。根据短文第一段最后一句话If you stand some distance(距离) away from the starter, you can see smoke from his gun before the sound reaches your ears.可知，看到烟雾要比听到声音早，即声音和光传播的并不是一样快的，其他三项表述错误；故选B。

3.推理判断题。根据短文第二段Sunlight(太阳光) takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays left the moon 1.3 seconds before they reached you.两句可知，太阳光传播的距离要远远大于月光；故选A。

4.推理判断题。根据短文最后一句话“The stars look pretty. They were shining four years ago, but their light has only just reached the earth.”可知我们今晚看到的星光是四年前就已经发射出来了，只是我们现在才看到；与C项描述相吻合；故选C。

考点：科普类短文阅读。