问题 问答题 简答题

爱因斯坦狭义相对论的两个基本前提及其主要内容是什么?

答案

参考答案:

两个前提:其一、相对性原理及科学规律包括电磁学规律相对任何惯性参照体系不变;其二、光速不变原理,及光速相对任何参照系保持不变。

结论:1、运动物体在运动方向上长度收缩;2、运动着的钟表变慢;3、光速时自然事物运动速度的极限;4、“同时”是相对的,在一个惯性系中同时发生的两个事件,在另一个惯性系看来就不定时同时的;5、当物质运动速度比光速小很多时,相对论力学就自自然过渡到牛顿力学,相对论更具普遍性;6、物质的能量等于惯性质量乘以光速的平方。

阅读理解

Have you felt annoyed when a cellphone rings during the class? Something must be done to stop this.Now in New York City, USA,a rule is carried out in schools.Students can’t even bring cellphones to schoo1.Is it a good thing or not?

Anxious parents say that cellphones are an important tool in holding New York city’s families together.

“I worry about it,” said Elizabeth Lorris Ritter, a mother of a middle school kid. It’s necessary in our everyday life.We have a washing machine. We have running water, and We have cellphones.”

Many American parents think cellphones connect them to their children on buses,getting out from subways, walking through unknown places.

“I have her call me when she gets out of school,”said Lindsay Walt, a schoolgirl’s mother. “No one in New York is going to let their child go to school without a cellphone”

What about the cellphone owners, the students? Most of the students said cellphones were essential and the cellphone was like all extra(额外的)hand or foot for them.

“I feel so empty,”said May Chom,1 4.There is also no way to listen to music on the way to school without my phone.It will be a really, really boring trip.”

小题1:You can use a cellphone___________.

A.to enjoy listening to music

B.to work as running water

C.to work as a washing machine

D.to send children to school小题2:Which of the following statements is TRUE?

A. Many American parents don’t think cellphones are necessary for the students.

B.Cellphones only bring troubles to the school life.

C. Cellphones connect children with their families when they are outside.

D. All the school children agreed not to use cellphones at school.小题3:What does the underlined word “essential” mean in Chinese?

A.时髦的.

B.必要的.

C.昂贵的.

D.浪费的小题4:The article is about the____ in carrying out the rule not to use a cellphone in schoo1.

A.happiness

B.interest

C.problem

D.satisfaction

多项选择题