Light travels at a speed which is about

题型:阅读理解

问题:

Light travels at a speed which is about a million times faster than the speed of sound. You can get some idea of this difference by watching the start of a race. If you stand some distance(距离) away from the starter, you can see smoke from his gun before the sound reaches your ears.

This great speed of light produces some strange facts. Sunlight(太阳光) 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 reached you. The nearest star is so far away that the light that you can see from it tonight started to travel towards you four years ago at a speed of nearly 2 million km. per minute. In some cases, the light from one of tonight’s stars had started on its journey to you before you were born.

Thus, if we want to be honest, we can’t say, “The stars are shining tonight.” We have to say instead, “The stars look pretty. They were shining four years ago, but their light has only just reached the earth.”

小题1:Light speed is ______ sound speed.

A.as fast as

B.a million times slower than

C.about millions of times faster than

D.about a million times faster than小题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 sound before you see the smoke

B.the sound does not travel as fast as light

C.the sound will reach you before the man fires

D.sound travels about a million times faster than light小题3:Sunlight obviously(显然的) ______ than the light of the moon.

A.has to travel a greater distance

B.moves less quickly

C.travels much more quickly

D.is less powerful小题4: The scientific way of saying "The stars are shining tonight" should be ______.

A.the stars have been shining all the time

B.the stars seen tonight will shine four years later

C.the stars were shining long ago but seen tonight

D.the starlight seen today could be seen four years ago

考点:健康环保类阅读科教类阅读
题型:阅读理解

()清代的票号是以经营汇兑为主的信用机构,为山西人首创。

题型:阅读理解

阅读下面古诗文,完成问题。

于郡城送明卿之江西

(明)李攀龙

青枫飒飒雨凄凄,秋色遥看人楚迷。

谁向孤舟怜逐客,白云相送大江西。

【注释】:(1)明卿:作者的好友。(2)楚:楚地(3)逐客:被贬逐的官员,这里指明卿。

1.这首诗前两句写出了环境_______、_______的特点。

2.这首诗表达了诗人怎样的情感?

____________________________________________________

题型:阅读理解

在脚手架上纵移换梁适用于()。

A、桥孔不便搭设临时墩架处

B、钢梁和16m及以下钢筋混凝土梁

C、更换便桥

D、墩台不高或邻线可利用处

题型:阅读理解

()属于职权范围内的签发。

题型:阅读理解

水电站可分为哪几种类型?

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