Light travels at a speed which is about a million times faster than the speed of sound. In one second, light travels about 300,000km, but sound travels only 344m. You can get some idea of this difference by watching the start of a race. If you stand some distance away from the starter, you can see smoke come from his gun before the sound reaches your ears. This great speed of light produces some strange facts. Sunlight takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays（光线）left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light which 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 started on its journey to you before you were born.

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

Light speed is ________ than sound speed.

A. millions times faster               B. a million times slower

C. about millions of times faster       D. about a million times faster

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 gun before you see the smoke.

B. sound does not travel as fast as light.

C. the sound of the gun will reach you before the man fires his gun.

D. sound travels about a million times faster than light.

What does “ it” refer to?

A. moon light    B. light rays         C. the nearest star        D. the moon

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 be shining four years later.

C. the stars were shining long ago but are seen tonight.

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

Light travels at a speed which is about a million times faster than the speed of sound. In one second, light travels about 300,000km, but sound travels only 344m. You can get some idea of this difference by watching the start of a race. If you stand some distance away from the starter, you can see smoke come from his gun before the sound reaches your ears. This great speed of light produces some strange facts. Sunlight takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays（光线）left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light which 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 started on its journey to you before you were born.
Thus, if we want to be honest, we cannot say “ The stars are shining tonight.” We have to say, “ The stars look pretty. They were shining four years ago but their light has only just reached Earth.”
【小题1】 Light speed is ________ than sound speed.

Light travels at a speed which is about a million times faster than the speed of sound. In one second, light travels about 300,000km, but sound travels only 344m. You can get some idea of this difference by watching the start of a race. If you stand some distance away from the starter, you can see smoke come from his gun before the sound reaches your ears. This great speed of light produces some strange facts. Sunlight takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays（光线）left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light which 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 started on its journey to you before you were born.

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

1. Light speed is ________ than sound speed.

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

3.What does “ it” refer to?

4.The scientific way of saying “ The stars are shining tonight” should be________.

Although April did not bring us the rains we all hoped for, and although the Central Valley doesn’t generally experience the sound and lightning that can go with those rains, it’s still important for parents to be able to answer the youthful questions about thunder and lightning.

The reason these two wonders of nature are so difficult for many adults to explain to children is that they are not very well understood by adults themselves. For example, did you know that the lightning we see flashing down to the earth from a cloud is actually flashing up to a cloud from the earth? Our eyes trick us into thinking we see a downward motion when it’s actually the other way around. But then, if we believed only what we think and we see, we’d still insist that the sun rises in the morning and sets at night.

Most lightning flashes take place inside a cloud, and only a relative few can be seen jumping between two clouds or between earth and a cloud. But, with about 2,000 thunderstorms taking place above the earth every minute of the day and night, there’s enough activity to produce about 100 lightning strikes on earth every second.

Parents can use thunder and lightning to help their children learn more about the world around them. When children understand that the light of the lightning flashing reaches their eyes almost at the same moment, but the sound of the thunder takes about 5 seconds to travel just one mile, they can begin to time the interval (间隔) between the flash and the crash to learn how lose they were to the actual spark (闪光).

1.According to the author, in the area of the Central Valley____.

2.We believe that lightning is a downward motion because_______.

3.What is TRUE about lightning according to the passage?

4.The underlined word “activity”  is most closely related to the word (s) _____.

5.It can be concluded from the passage that _______.

Although April did not bring us the rains we all hoped for, and although the Central Valley doesn’t generally experience the sound and lightning that can go with those rains, it’s still important for parents to be able to answer the youthful questions about thunder and lightning.

The reason these two wonders of nature are so difficult for many adults to explain to children is that they are not very well understood by adults themselves. For example, do you know that the lightning we see flashing down to the earth from a cloud is actually flashing up to a cloud from the earth? Our eyes trick us into thinking we see a downward motion when it’s actually the other way round. But then, if we believed only what we think and we see, we’d still insist that the sun rises in the morning and sets at night.

Most lightning flashes take place inside a cloud, and only a relative few can be seen jumping between two clouds or between earth and a cloud.  But, with about 2,000 thunderstorms taking place above the earth every minute of the day and night, there’s enough activity to produce about 100 lightning strikes on earth every second.

Parents can use thunder and lightning to help their children learn more about the world around them. When children understand that the light of lightning flashing reaches their eyes almost at the same moment, but the sound of the thunder takes about 5 seconds to travel just one mile, they can begin to time the interval(间隔) between the flash and the crash to learn how close they are to the actual spark(闪光).

36. According to the author, in the area of the Central Valley, ___________.

A. rains usually come without thunder and lightning 

B. it is usually dry in April

C. children pay no attention to the two natural wonders

D. parents are not interested in thunder and lightning

37. We believe that lightning is a downward motion because ___________.

A. we were taught so by our parents from our childhood

B. we are taken in by our sense of vision

C. it is a common natural sight

D. it is a truth proved by science

38. What is TRUE about lightning according to the passage?

  A. Only a small number of lightning flashes occur on earth.

  B. Lightning travels 5 times faster than thunder.

  C. Lightning flashes usually jump from one cloud to another.

  D. There are far more lightning strikes occurring on earth than we can imagine.

39. The underlined word “activity” is most closely related to the word(s)  _______________.

A. “cloud”   B. “lightning strikes”   C. “lightning flashes”  D. “thunderstorms”

40. It can be concluded from the passage that____________.

  A. we should not believe what we see or hear

  B. things moving downward are more noticeable

  C. people often have wrong ideas about ordinary phenomena (现象)

  D. adults are not as good as children in observing certain natural phenomena