问题 计算题

已知地球半径为R,地球的同步卫星离地心的距离为r,设第一宇宙速度为v1,地球赤道上的物体随地球自转的向心加速度为a1;同步卫星的线速度为v2,向心加速度为a2,试求v1/v2和a1/a2各为多少?

答案

由万有引力等于向心力有:

从而有v=

所以:

因同步卫星与地球自转角速度相同,所以

阅读理解

阅读理解。

     Most American students go to traditional public schools.There are about 88, 000 public schools, all

over the US.Some students attend about 3000 independent public schools called charter schools.

     Charter schools are self-governing.Private companies operate some charter schools.They are similar

in some ways to traditional public schools.They receive tax money just as other public schools do.

Charter schools must prove to local or state governments that their students are learning.These

governments provide the schools with the agreement called a charter that permits them to operate.

     Charter schools are different because they do not have to obey most laws governing traditional public

schools.Local, state, or federal governments cannot tell them what to teach.Each school can choose its

own goals and decide the ways it wants to reach them.Class size is usually smaller than in traditional

public schools.

     The Bush Administration strongly supports charter schools as a way to re-organize public schools that

are failing to educate students.But some education agencies and unions oppose charter schools.One

teachers' union has just made public the results of the first national study comparing the progress of

students in traditional schools and charter schools.

     The American Federation of Teachers criticized the government's delay in releasing the results of the

study, which is called the National Assessment of Educational Progress.Union education experts say the

study shows that charter school students performed worse on math and reading tests than students in

regular public schools.

     Some experts say the study is not a fair look at charter schools because students in those schools

have more problems than students in traditional schools.Other education experts say the study results

should make charter school officials demand improved student progress.

1. If a private company wants to operate a charter school, it must______.

A. try new methods of teaching      

B. prove its management ability

C. obey the local and state laws      

D. get the government's permission

2.What's the government's attitude toward charter schools?

A. Doubtful    

B. Supportive.  

C. Subjective.  

D. Optimistic.

3. What can we learn from the text?

A. More students choose to attend charter schools.

B. Charter schools are better than traditional schools.

C. Students in charter schools are well educated.

D. People have different opinions about charter schools.

4. It can be interred from the text that ___.

A. charter schools are part of the public education system

B. one-on-one attention should be paid to students

C. the number of charter schools will be limited

D. charter schools are all privately financed    

写作题
请根据以下的情景说明,使用5个规范的英语句子描述所给的全部信息内容。
【写作内容】
假如你是一名中学生,叫李晓华,请根据下表内容用英语写信给某报社Just Ask栏目的主持人Ralph,请求帮助解决一个长期困扰你的问题。
你的情况
1. 学习成绩好
2. 爱母亲。
3. 有点害怕母亲。
你母亲的情况
1. 对你很严,易发脾气。
2. 很少有时间和你说话。
你的问题
1. 很少交流。
2. 希望互相了解。
3. 不知如何沟通。
【写作要求】
1.必须使用5个句子介绍所给的全部内容;
2.将5个句子组织成连贯的短文;
3.参考词汇:发脾气lose one’s temper;
4.开头和结尾已经给出,不计入总句子数。
【评分标准】
句子结构准确,信息内容完整,篇章结构连贯。
Dear Ralph,
I’m a middle school student.                                                                     
                                                                                                     
                                                                                                     
                                                                                                    
I do hope we’ll be closer.What can I do?Looking forward to your reply.
Best wishes!
Yours sincerely,
LiXiaohua