题目列表(包括答案和解析)
Light doesn’t travel as fast as sound, _______?
A. doesn’t it B. is it
C. does it D. do they
Light travels at a speed which is about a million times faster than the speed of sound. In a second, light travels about 300,000km, but sound travels only 340m. You can get some ideas 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 left the moon 1.3 seconds before they reach 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 20 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 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 slowerB
．about millions of times fasterC
．about a million times faster(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 gun before you see the smokeB
．sound doesn't travel as fast as lightC
．the sound of gun will reach you before the man fires his gun(3) Sunlight ________ to the earth than the light of the moon.
[ ]
A
．has to travel a greater distanceB
．moves less quicklyC
．is less powerful(4) The scientific way of saying
“the star are shining tonight”should be ________.[ ]
A
．the stars have been shining all the timeB
．the stars seen tonight will be shining four years laterC
．the stars were shining long ago but are seen tonight(5) The light of the nearest star you see tonight has been ________ for four years.
[ ]
|
A ．away from the star |
B ．on the moon |
C ．away from the sun |
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