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

　　Thus, if we want to be honest, we can not 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 the earth.”

　　阅读短文，选择最佳答案．

(1) The speed of light is ________ than the speed of sound.

A．a million times slower

B．about millions of times faster

C．about a million times faster

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

B．sound doesn't travel as fast as light

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

A．has to travel a greater distance

B．moves less quickly

C．is less powerful

(4) The scientific way of saying“the star 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