某中学高中部学生人数是初中部学生人数的[1/2]，高中部男生人数是女生人数的[5/7]，初中部男生人数是女生人数的1[1

4个班一个老师老师就太多了 一般一个老师教两个年级 每个年级3-4个班
这样一共大概要8-10个老师

少讲课程多做课外.尽量废话少说.
很多老师教书过程中,十有八废话多.学生每天获取新知识少.
布置作业要新的题型,并且坚持每天学生都获取新的知识.要严要密.

Ladies and gentlemen,
Good morning ． I’m Li Hua from Ningxia China ． It’s my great honor to be here to say something about global water shortage and ways of dealing with it ．
As we know, the global water shortage is becoming increasingly severe mainly due to global warming, environmental pollution and the ever-increasing population．Therefore, it’s high time we did something about it．
Firstly, an effective way, I think, is to reserve water in a scientific way for future use．Secondly, new methods need to be developed to use the existing water resources, for example, turning sea water into fresh water．Thirdly, we must stop water pollution by law．Last but not least, it’s everyone’s responsibility to make good use of water, such as recycling and saving water in our daily life．
In conclusion, people around the world should be aware of the real situation of water shortage, protect the present water resources and explore potential ones scientifically．
That’s all ． Thank you

略

解题思路：根据题干，要求初中学生和高中人数，需要求得这个中学的师生人数总数：这里是某中学高中学生、初中学生和教师的总人数看做单位“1”，教师100人是占总人数的10%，利用总人数=教师人数÷所占比例即可计算得出总人数；由此利用初中学生=总人数×初中学生所占比例；高中学生=总人数×高中学生所占比例即可解决问题．

100÷10%=1000（人），
初中人数为：1000×40%=400（人），
高中人数为：1000×50%=500（人）；
答：初中学生有400人，高中学生有500人．
故答案为：400；500．

点评：
本题考点： 扇形统计图；百分数的实际应用．

考点点评： 本题考查的是扇形统计图的综合运用．读懂统计图，从统计图中得到必要的信息是解决问题的关键．扇形统计图直接反映部分占总体的百分比大小．

一般完成时:havehas+动词的过去分词
一般完成进行时：havehas+doing

加我

One possible version:
Dear Peter,
I was so glad to receive your letter dated August 31, 2013. As you request, I’ll tell you something about my school life.
Firstly, I’ll tell you something about my teachers and classmates. My first impression of my teachers was that they are enthusiastic and friendly, and as a result, we are on good terms with each other. And there are 30 students in my class, most of whom are kind and helpful, so we get on well with each other.
Secondly, I’ll tell you something about our studies. Before class, we often preview the lessons and some other materials related to our class. In class, the teachers guide us to learn and explore the knowledge with the learning papers. After class, we always discuss in groups and try to solve the problems together.
Thirdly, we also have various after-school activities. I joined a dance club, and we practice dancing together every Tuesday. Besides there are sports meetings and parties each term. What’s more, we also have other social practice, for example, we go to the nursing house to visit the disabled children or the old people every year.
It’s really funny to be in our school. And I will be delighted if you can tell me something about your school. I’m looking forward to your reply.
Yours,   

解题思路：根据学生总数和要抽取的人数，求出三个年级要抽取的人数，其后的问题是一个古典概型，做出试验发生包含的事件是从9个人中抽取2个和满足条件的事件抽到的这2名同学都是高一学生，根据古典概型概率公式得到结果．

∵中学高中学生有900名，
学校要从中选出9名同学作为校庆活动的志愿者，
∴每个个体被抽到的概率是[9/900]=[1/100]，
∴从高一抽400×[1/100]=4名学生，
从高二抽300×[1/100]=3名学生，
从高三抽200×[1/100]=2名学生，
由题意知本题是一个古典概型，
∵试验发生包含的事件是从9个人中抽取2个人，共有C₉²=36种结果，
满足条件的事件是抽到的这2名同学都是高一学生，共有C₄²=6
∴抽到的这2名同学都是高一学生的概率是[6/36＝
1
6]，
故答案为：[1/6]

点评：
本题考点： 古典概型及其概率计算公式．

考点点评： 本题考查古典概型及其概率公式，考查分层抽样方法，考查用排列组合数表示事件数，考查利用概率知识解决实际问题，本题是一个综合题目．

Water is the essence of life. All creatures evolved out of marine life. Even the creationist view of life does not exclude the importance of water. Our body is 55% to 75% water (depending on age and health, with decreasing percentage with increasing biological age), and our cells are 70% to 90% water. Dehydration is one major effect of ageing, and this can be clearly seen in the ageing skin.
Water is not only essential to the health of our bodies, but also to the health of our earth. The gaia concept views earth as a living organism which, like all living organisms, depends much on clean, health-giving water.
Unfortunately, our blatant neglect of the lakes, rivers, and oceans, and our persistent pollution of the environment has contaminated most of our water sources. Some of the rivers that flow through major cities around the world are so murky, only mutant fish can survive! As clean water sources are becoming scarce, in future, wars will be fought over water, and not just oil.
Sometimes, we will meet the problem of shortage of water.This problem is quick hard and we must handle it quickly for our future or our lovely generations. If you have knew how important water is, please take better care of our nature, especially the water for our daily life!

高一年级刺激偶去的学生数为 45-15-10=20，每个个体被抽到的概率等于
20
400 =
1
20 ，
高中部的学生数为 45÷
1
20 =900，
故答案为：900．

One possible version
Ladies and gentlemen,
Good morning. I’m Li Hua from Fujian, China. It’s my great honor to be here to say something about the global water shortage and ways of dealing with it.
As we know, the global water shortage is becoming increasingly severe mainly due to global warming, environmental pollution and the ever-increasing population. Therefore, it’s high time we did something about it.
Firstly, an effective way, I think, is to reserve water in a scientific way for future use. Secondly, new methods need to be developed to use the existing water resources, for example, turning sea water into fresh water. Thirdly, we must stop water opllution by law. Last but not least, it’s everyone’s responsibility to make good use of water, such as recycling and saving water in our daily life.
In conclusion, people around the world should be aware of the real situation of water shortage, protect the present water resources and explore potential ones scientifically.
That’s all. Thank you.

略

高一年级刺激偶去的学生数为 45-15-10=20，每个个体被抽到的概率等于 [20/400]=[1/20]，
高中部的学生数为 45÷[1/20]=900，
故答案为：900．

解题思路：由已知，样本容量为 ，所以，高中二年级被抽取的人数为 ，选 .

D


<>