阅读理解。
Light reflecting
You cannot see any object unless light from that object gets into your eyes. Some of the things you see
give off light of their own. The sun, the stars, a lighted lamp are the examples that can be seen by their own
light. Such things areluminous, most of the things you see are not giving off light of their own. They are
simply reflecting light that falls on them from the sun or some other luminous body. The moon, for
example, doesn't give off any light of its own. It is nonluminous. You see it because sunlight falls on it and
some of it reflects in our direction. So moonlight is only second-hand sunlight.
When you look at a book, it sends some of the light which falls on it to your eyes, and you see the
book. If light could be kept out from where you are so that there would be no light from the book to
reflect, then you could not see the book even with your eyes wide open. Light travels so fast that the time
in which it travels from the book you are reading to your eyes is as short as if there were no time at all.
Light reaches us from the moon, which is about 380, 000 kilometers away, in only a little more than a
second.
1. You can see the book because _____.
A. your eyes are close to it
B. it reflects some of the light
C. it has light of its own
D. your eyesight can get to it
2. The underlined word "luminous" means "_____".
A. can't be seen
B. can be seen
C. giving off light
D. not like sunlight
3. _____ have light of their own.
A. The sun and the moon
B. The stars and the earth
C. The sun and the stars
D. The moon and the earth
4. Light travels about _____ kilometers per second.
A. 380,000
B. 100,000
C. 400,000
D. 190,000
5. Which of the following is TRUE?
A. All the things you can see give off light.
B. Light from the book is much shorter than that from the moon.
C. The moment you open your eyes, the light from the book travels to your eyes.
D. Light travels so fast that there is no time for you to read.

查看答案