Question

If someone asks you, “What colour is the sky?” I think you will answer “blue”. I’m afraid that you will be wrong. The sky has no colour. It looks blue because we are looking at the blue sunlight. The sunlight is shining on little bits of dust(灰尘) in the air.

Is the sky full of air? I’m sure that you have asked this question, too. We know that there is air all around the world, but we couldn’t fly very high because as we go high, the air gets thinner. If we go far enough away from the earth, we find there is no air.

Maybe we can answer some questions now. What is the sky? Where is it? It is all round the world. The sky is space(宇宙空间). In space there is nothing, but only the sun, the moon, the earth and all the other stars.

1.The sky is ______.

A. a star round the earth

B. a big ball with air

C. full of dust

D. space with the sun, the moon, the earth and many other stars

2.What makes us think the sky is blue?

A. Dust in the sky.     B. Air and blue light.

C. Our own feeling.     D. Both A and B.

3.We can’t fly very high because ______.

A. there’s too much air in the sky

B. the high sky is full of dirty air

C. there’s no air in the high enough sky

D. the sun is too hot

Answer

1.D

2.D

3.C

【解析】

试题分析：本篇文章主要解释了几个问题：（1）为什天空是蓝色的；（2）天空中充满了空气吗：（3）天空是什么。

1.1】D细节理解题。根据文章内容The sky is space(宇宙空间). In space there is nothing, but only the sun, the moon, the earth and all the other stars.可知天空是宇宙空间。除了太阳，月亮，地球和一些其他的星星，什么都没有的太空。答案为D。

2.2】D细节理解题。根据文章内容It looks blue because we are looking at the blue sunlight. The sunlight is shining on little bits of dust(灰尘) in the air.可知我们看着天空是蓝色的，因为我们看着蓝色的太阳光，阳光因为空气中的灰尘就发蓝光。可推断答案为D。

3.3】C细节理解题。根据文章内容We know that there is air all around the world, but we couldn’t fly very high because as we go high, the air gets thinner.我们飞不高，因为越向上空气越少。可知答案为C。

考点：考查科普类阅读。