Stopreadingforaminuteandthinkaboutwhatyouseewhenyoulook...

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Stop reading for a minute and think about what you see when you look up at the sky on a clear night. You probably see many stars. Long long ago, farmers watched some stars to know when to plant their crops. Travellers did so to find their ways in the dark. Today stars are still important to some people.

Scientists found out that most stars are very big. In fact some stars are so far away that it would take millions of years to get to them even by spaceship.

Another thing we know today about stars is that some are made up of hot gases (氣體). The gases are so hot that they send out light. If you watch a star carefully, you may notice that it twinkles (閃爍) sometimes. As you may understand, light from a star must shine through the air before you can see the star. Air is always moving, it makes light from the star move back and forth (前後). When the light moves, it makes the star twinkle. Stars also have different colors. The color of a star depends on how hot it is. To our surprise, the cool stars are red and the hottest are blue white.

1. The speaker asked us _____.

A. to stop looking up at the sky for a minute on a clear night

B. to think about what we saw when we looked up at the sky on a clear night

C. to stop to have a rest and look up at the sky

D. to stop reading for a minute and look up at the sky

2. Long long ago, travellers _____ to find their ways in the dark.

A. made a fire B. used a map C. watched stars D. asked farmers

3. Why does a star sometimes twinkle? Because _____.

A. its light travels through the moving air B. its light is too bright

C. it is very big D. it shines when you move back and forth

4. What is the color of the hottest stars? They are _____.

A. red B. yellow C. white D. blue white