问题 填空题

如图所示,泥瓦工砌墙时常用细线拴一小砖瓦或碎石,挂吊在墙边,其作用是______,工作原理是______.

答案

重力的方向是竖直向下的,它的最重要的一个应用就是:砖工师傅常用重垂线检查墙砌得是否竖直.

根据重力的方向始终竖直向下;如果墙壁和重锤线是平行的,墙壁是竖直的,否则墙壁不竖直.

故答案为:测量所砌墙体是否竖直,重力的方向是竖直向下的.

阅读理解

We have always been interested in the moon.2000 years ago, people already knew that the moon moves around the earth and where it would be in the sky at different times of the year. At that time, everything about the moon was learned by watching it carefully in the sky.

When scientists could use telescopes to study the moon more closely, their ideas began to change. They could see the moon was made of rocks. Most scientists thought moon rocks would be different from those on the earth. This was because they believed the moon had once been a planet that had been caught in the earth’s gravity millions of years earlier.

In 1969, moon rocks werefinally brought to the earth and studied. Much to their surprise, scientists found that, except for water, the moon and the earth were made of the same things. Once again new ideas were needed for this new information.

After years of study, most scientists now think that the moon was once part of the earth. They believe very early in its history, maybe 4 billion years ago, something about the size of Mars hit the earth. This sent billions of rocks into space around our planet. These rocks slowly joined together and after many years became the moon.

In the future, even thought our ideas about the moon may change again, we will still be interested in it.

小题1:2000 years ago, people already knew_____.

A.the earth moved around the moon

B.the moon and the earth were made of the same things

C.the moon was made of rocks

D.the moon moves around the earth小题2:Before 1969, most scientists thought the moon was_____.

A.part of the earth billions of years earlier

B.older than the earth

C.a planet caught by the earth’s gravity

D.made of the same things as the earth小题3:After years of study, most scientists now think_____.

A.the earth was once part of the moon

B.the moon was once part of the earth

C.something about the size of Mars will hit earth in the near future

D.a lot of rocks will slowly join together to become the other moon小题4:From this passage we can learn that_____.

A.scientists in the past were not clever

B.scientists are so clever that they know everything

C.new information brings new ideas

D.we now everything about the moon

填空题