"You'll think twice about plucking your eyebrows (拔眉毛) you find their important role," says Greg Foot. They are one of most expressive(有表现力的) parts of our bodies. your eyebrows, you can tell your feelings to other people. is that their only purpose (目的)?

    Over several thousand (year), we have lost lots of body hair, so it's strange that hair still (remain) on our brows. Some scientists say that eyebrows mainly work as special form of protection for the eyes. In fact, their job is so (importance) that some researchers are sure that if we didn't have (they), we'd have evolved (进化) some other facial features to (do) the same task.

    Light travels at a very fast speed. It is about a million times 1 than the speed of sound. You can get some idea of this 2 by watching the start of a race (赛跑). If you stand some distance away from the starter, you can see smoke from his gun before the sound gets to your 3

    This great speed of light4some strange facts. Sunlight 5about 8 minutes to get to us. If you look at the light of the moon tonight, 6 that the light rays (光线) left the moon 1.3 seconds before they got to you. The nearest star is so 7 away that the light which you can see from it tonight started to 8 towards you several years ago. In some cases, the light from one of tonight's stars had started on its journey to you before you were born.

    So, to be exact, we can't say, "The stars are shinning 9." We have to say instead, "The stars 10 pretty. They were shining several years ago, but their light has only just got to the Earth."

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