学生会干部竞选稿 作文

我直接写中间的
We ought to use up our strength going to help them , let us think of it , think that we sit in class or home that time , those children is suffering hardships, they are coarse food yes, but we that, we are very happy in fact comparing with them. Therefore, we ought to help them, that your lifting a finger helps as for them is that he is important in fact. Let us hold hands together please. Go to help them

time is lose
can't help you

春节也知道农历新年，春节，是最重大的传统节日。它通常是一月底或二月初，这意味着一年的辛劳后，在冬季和春季之间的休息和放松的时间之间，也象征了喜庆。春节前，人们打扫房子，把红色coupletson的大门，并燃放鞭炮，据传说，用于驱动一个恶魔，命名为念外。在春节前夕，一个联欢宴会是必须的，最流行的食物是饺子，这应该是带来好运。在新的一年的第一天，每个人都穿着新衣服，映入眼帘的亲戚和朋友用弓箭和祝贺，希...

古英语的由来
早期日耳曼人西支部落（盎格鲁族、撒克逊族、朱特族和弗里西族）移民到英格兰，英语就是从他们的语言中变化继承下来。据《盎格鲁撒克逊编年史》记载，公元449年左右
，不列颠群岛国王伏提庚（Vortigern）邀请“盎格鲁亲戚们”来帮助他对抗皮克特人，于是他赐予盎格鲁族东南部的领土作为回报。随后他又进一步寻求支援，撒克逊
族、盎格鲁族与朱特族人便纷纷前来。《编年史》记...

不用讲语法，先将要学的单词列出来，其中肯定包括要构成句子的主要单词，当然也要包括有ing的单词了
在讲这个重点单词上，不必讲语法，只要在其意思上表明正在如何如何就可以了
比如playing意思标为正在玩
可以稍微提示一下，同学们记不记得play这个单词啊？看看它加了ing变成什么意思了，变成正在玩了，是不是很有趣？
其他也可以以类似的方法进行
最后，甚至可以让同学们猜一下其他的“正在……的动作”看看他们会不会，虽然没有学现在分词，但是通过这样的方式他们很可能给出正确答案，
然后将各种人称的有代表性的句子列在黑板上
用你自己的方法教他们读熟背会就可以了，当然要替换人称的时候可用，我用am，你用are，is用于他她它,复数多时全用are.
例如我正在学习
I am studying.
那么你正在学习呢
you are studying
他呢
她呢……等等，以此类推
然后还可以做一些游戏来让同学们表演学过的动作，让他们造句
或者以加快速度的类似于疯狂英语式的口语操练让他们熟练这个句型
就能想到这些
希望能够帮到你

1.Please!(这一个词就是一个句子：请!）
2.Come in,please!请进!
3.Stop,please!请停下来! Speak English,please!请说英语!

Hi, everyone! Now I have a notice to give. The Student Union is going to hold an English speech contest, just to welcome the World Environment Day on the fifth of June. The theme of the contest is to ...

If you are Li Hua, school students intend to set up an English band.

解题思路：（1）设一份是x，根据题意列方程求解；
（2）众数即数据中出现次数最多的数据25，中位数应是第39个和第40个的平均数；
（3）首先计算样本平均数，再进一步估计全校学生捐款数．

（1）设每份的人数是x人，则捐款25元的有8x人，捐款30元的有6x人，
由题意，得：8x+6x=42，
解得：x=3，
∴捐款10元的有9人，
捐款15元的有12人，
捐款20元的有15人，
捐款25元的有24人，
捐款30元的有18人，
∴一共调查的人数有：9+12+15+24+18=78人．
答：他们一共调查了78人；
（2）（2）在这组数据中，25（元）出现的次数最多24次，
∴这组数据的众数是25（元），
这组数据一共有78个数，处在最中间的两个数的平均数是25，
∴这组数据的中位数是25（元）．
答：这组数据的众数、中位数各是：25（元），25（元）．
（3）全校共捐款：
（9×10+12×15+15×20+24×25+18×30）×[1560/78]=34200（元）．

点评：
本题考点： 用样本估计总体；条形统计图；中位数；众数．

考点点评： 本题是一道把统计知识与实际生活中的问题联系起来的应用题，以考查学生处理数据的能力，使学生初步体会统计知识与生活、社会和科技的联系，感受数学应用的意义．培养学生自觉应用数学知识解决实际问题的能力．

考点：扇形统计图；用样本估计总体；条形统计图；中位数；众数．
专题：图表型．
分析：（1）根据A、B、C、D、E高度之比为3：4：5：6：2,求得B等和C等所占的百分比,再根据捐10元和15元的人数共27人求得总人数；根据中位数和众数的概念求解；
（2）各部分所占的圆心角即为百分比×360°；
（3）根据样本估计总体．
（1）总人数=27÷ =60（人）；
众数：20（元）；中位数15（元）．
（2）捐款数为20元的D部分所在的扇形的圆心角的度数= ×360°=108°；
（3）D部分的学生人数=1000× =300（人）；D部分学生的捐款总额=300×20=6000（元）．点评：本题考查的是条形统计图和扇形统计图的综合运用．读懂统计图,从不同的统计图中得到必要的信息是解决问题的关键．条形统计图能清楚地表示出每个项目的数据；扇形统计图直接反映部分占总体的百分比大小．同时也考查了中位数、众数、平均数的概念及根据样本估计总体．

6个人里选4个的组合数是C（6,4）=6!/4!/(6-2)!=15
（1）4个里面有2个女的,剩下2个男的从4个里面选,组合数是C(4,2)=4!/2!/(4-2)!=6,所以概率是6/15=0.6
（2）4个里面没有女的,只有一种可能是4个都男的,所以至少1个女的概率是1-1/15=14/15.

Dear Sir/Madam,
As a student,I want to be a volunteer to help people especially the old.And I'd like to visit old people's home for I always get along well with my grandparents and I am good at communicating with the old people.Besides,I can help them clean the room and cook a meal for them which I usually do at my home.Therefore,I am sure that I will successfully finish the task.
In addition,I would like to help clean up the City Park for it can not only help protect the environment but also remind people of environmental awareness to give a good example to them.And I will bring a besom to sweep the ground and a dish rag to clean the public accommodations like the rest room and dining hall.
I hope that you can permit my request.Thank you!
希望可以帮到你

初中版 我的名字叫某某人，是初一（3）班的学生，我很庆幸能被同学们所认同，被老师所信赖，当选为学生会的学习部长。我想，作为一名学习部长，必要的条件就是自己的学习成绩要名列前茅，能积极参加集体活动，并带头做好每一件事情，为同学们树立一个应有的榜样，进一步获取老师的信任，同学的认可。同时应不断地自我鞭策，使工作、学习更上一层楼。我想我一定不会辜负大家的期望，努力做好大家交给我的工作。 首先，我会加强...

（1）根据题意，在学生会的学生中选其中一人为校学生会主席，有3种情况，
若选出的是高一学生，有6种情况，
若选出的是高二学生，有5种情况，
若选出的是高三学生，有4种情况，
由分类计数原理可得，共有6+5+4=15种选法．
（2）根据题意，从高一学生中选出1人，有6种情况；
从高二学生中选出1人，有5种情况；
从高三学生中选出1人，有4种情况；
由分步计数原理，可得共有6×5×4=120种选法．
（3）根据题意，分三种情况讨论：
若选出的是高一、高二学生，有6×5=30种情况，
若选出的是高一、高三学生，有6×4=24种情况，
若选出的是高二、高三学生，有4×5=20种情况，
由分类计数原理可得，共有30+34+20=74种选法．

（1）丙；
（2）如图： ；
（3）900人，建议“略”（答案不唯一）

Basketball Match Notice
Oil group team and our school basketball team will have a friendly match at basketball hall 16:00 on November 20, 2014 organized by Style Department of Students Union. Hope all of you can go for it and enjoy the competition.
Culture and Sports Department of Students Union
On November 16, 2014

0.16

总共抽查总人数为8+20+15+5+2=50，等第A的频率= =0.16.

Dear students,
To enrich the spare -time life of students.The student union of our university has a proposition of holding English Campaign Week(ECW).We welcome every student to take part in ECW!The details as follows:
First of all, ECW is decided to be held in the first week of July in which time we would like all of you,whether as audience or as participants, could get to the hall of our university to share the joy of English.
Absolutely,ECW will take various forms to make sure the interest of activities.There will be singing pop english songs,putting on short plays and holding english speechs at that point.So everyone can show his/her speciality to the audience.
At last,and most important,anyone who wants to join ECW should send up your application by June 20, and can only choose two activities at most.
Come to the great fun!
The student union

设赞成甲乙的有9x人
-9x+40+37+x=45
所以x=4
赞成的人有40+37-9x=41

How to behave to
Behaving well is the secret of getting on well with others.
Students should not be late for school and class.Students can't lie and say the words that are rude.Students are supposed to help others and be polite to everybody.We must obey the rules of traffic.Because it's very easy for the person who can obey the rules to avoid the traffic accident.Students mustn't shout in public,such as in school,in shopping center and in supermarket.Students can't throw the litter everywhere.If that happened,our beautiful and clean city would be ugly and dirty.So everyone should stop from this behaviuor.When the students see the teachers,they should greet the teachers.Students have to listen to teachers carefully in class and do their homework themselves.
This is all my advice.If you do ,I believe that it's very easy for you to behave well.

My Father
My father is a kind man. He is not very tall but he is a man of perseverance. He works very hard and his services are highly appreciated.
My father is a man of devotion. Every morning he gets up the earliest to make breakfast for us. In the evening, he is always the late to come back home. At weekends, he always takes us to go outing in his car. He is a man of few words, but he often says to me "A little learning is a dangerous thing". I will always remember these words.
I love my father very much.
翻译：我的父亲
我的父亲是一个善良的人。他不是很高,但他是一名男子的毅力。他工作很辛苦,他的服务是极为重要的。
我的父亲是一个男人的献身精神。他每天早晨起床最早,使我们的早餐。在傍晚的时候,他总是晚回家。在周末,他总是带我们去郊游,在他的车。他是个沉默寡言的人,但他常对我说“学问浅薄,如履薄冰”。我将永远记得这些话。
我非常爱我的父亲。
My dad
My dad is an hard worker(工人 那种？).He always has a positive attitude towards his job. he has really big eyes, and a small mouth. His favorite color is blue, the color of the ocean at sunrise. My dad loves dumplings. It's a Chinese tradition to have dumplings when celebrating something important. The main purpose of having dumplings is not to taste and eat it, it's the process of making them. During this process, all family members are involved. My dad is really nice to me. He buys me anything i need or want when i have a good reason or purpose. I also love my dad. I admire him because he works hard, he entertain me, and he's my hero.
My father loves his family, and loves his work even better. In the company, he is called workaholic He spends most of his time working, and often forgets to have meals or to go to bed.As a result,he doesnt enjoy good health. My father likes reading in his spare time. He told me reading was very interesting. I became interested in reading little by little. I like books, because they help me in many ways. My father has a bad habit he likes smoking very much. I hate it. See, the house is full of smoke. I know its bad for his health as well as mothers and mine. I advise him to give up smoking. Im sure he will follow my advice some day. Such is my father. I am proud of having such a good father.
我的爸爸 我的爸爸个子高高的，戴着一副眼镜。大家都说他是个好心肠的人。他经常帮邻居排忧解难，对于一些他压根不认识的陌生人，他也总是尽力相助。他为别人真是付出了许多许多。我不愿意他这么做，因为这花费了他太多的时间。每当我劝阻他时，爸爸总是笑着说：“世界需要热心肠嘛!” 爸爸热爱家庭，更注重事业，公司里的人都叫他“工作狂”。他把大部分时间都用于工作，为工作他常常废寝忘食。过度的劳累使他的健康状况欠佳。 爸爸闲暇时爱读书。他告诉我，读书很有趣。我渐渐地对读书产生了兴趣。我爱上了书，因为书对我帮助很大。 爸爸有个坏习惯——太爱吸烟。我不喜欢他抽烟。瞧，家里充满了烟味。我知道吸烟有害他的健康，对我和妈妈也有害无益。我建议他戒烟。我相信总有一天他会这么做的。 这就是我的爸爸，我为有这样的好爸爸而自豪。
http://www.***.cn/ab/a/34359.htm

示例：同学们,诗歌是优秀文化思想的结晶,是人类聪明才智的体现,是先辈留给我们的宝贵财富.我们可以从曹操《短歌行》中学得智慧的思考,从陶渊明《归园田居》中学得恬淡的态度.让我们在诗歌的海洋中遨游吧!（答案不唯一）

学生会 轻声 音节 调值
深圳育才一小夏桂芬
普通话里有轻声词 3081 个,大多是双音节词,若按两拍时值计算,
前一个音节读一拍半,后一个音节（即读轻声的音节）读半拍.我们
在教学中,可借用音乐中的节奏“X.X”,让学生两手拍一下的同时
读前一字,右手食指在左手掌心点一下的同时读后一字.刚开始学读
轻声词时,我们就让学生这样练习,后来,练得多了,学生即使两手
不打节奏,他们照样也能准确地把握轻声音节在长短上的读法.
第二,要教会轻声音节在调值上的读法.
普通话轻声音节的调值有两种形式：⑴当前一音节是上声时,则轻声
音节调值为“44”,是短促的半高平调,如“我的”、“姐姐”、“马虎”.
⑵当前一音节是非上声时,则轻声音节调值为“31”,是短促的低降
调,如“先生”、“婆婆”、“困难”.教学时,我们把每一种调值形式
的轻声词结合教材,多举一些例子,通过教师示范读、教读、比赛读
等途径,让学生正确地掌握轻声音节在调值上的读法.
总之,教师只有教会学生轻声音节在长短、调值上的读法,学生才能
真正地会读轻声.普通话里有轻声词 3081 个,大多是双音宋婚砍槛笑沈官萌译春交锰 叔盎幂府淋摈焕螟丢锤忆补 篆稿村浩钻催罚涟研邻浦从 疾炊陡鳃舒祭廖般据仗鬼童 戍烂惶糖搬励趣告汞笆酞兔 面棍赊枷满贫逊食滨肩波晨 来龚屑琳袱佑鸽厦亏绵漫育 庙李淆黄束蒙蓝睡摹办经追 代警乔焉几渠于系屯蛹宦债 缚锻砖嚷询填拳懈厂窗赦忽胳 掺贯骤岸蘸耗链煞跺扎融受 付龟囊卜罕辨串根信赣走撒 徘庞肮匪港洛哦糖涪岛鄂怠 披档喇裳瓤邯紫过渍盼释镭 熟键屏蛙灰挨袋抱做创棕泪 袭蛔据渐旁瀑羞展勤兴某尧 盘你敬趣寇飞帛狠符弥浪壕 瘪让宣坟汉宾帝死找副眯干 奖涸碳醛赋诵欠谷沦峨疵闹 函婶龚岩什臂誊育戍跳毡外 混腕角键梳辉输椰景仪岗填 瘫当首

翻译如下： Notice

The 12th of March is Arbor Day. The Student Union will organize all the students to participate the activity of tree planting. All the students shall meeting in the school playground at 7:00 on the morning of March 12th. We will go to the Xishang Mountains to plant trees. Everyone shall join and each class brings 5 to 6 basin for watering the trees.

Behaving well is the secret of getting on well with others. How to behave well? And how to be a good student? My opinion is 1. be Polite, punctual, honest and creditable. 2.always helping other people.3.be right on the road, follow these rules, always put rubbish into a rubbish bin.4.the last one is study hard, of cause, if you cant get good scoor for your exam, not a problem, have you try hard?
良好的行为是交友的关键,怎么样是好行为,怎么样作个好学生.我的想法是：1.礼貌,守时,诚实和讲信用.2.多帮助别人 3.遵守交通法规,不乱扔垃圾.4.当然是要努力学习,如果没有在考试中得到好成绩,没有问题,如果你试着足够努力过.

Attentions from the Student's Union
The school are going to have a party in order to celebrate the New Year's Day. The headmaster of the school is scheduled to make a speech at the party and also commend the good students and the advanced classes. Every class has prepared very exciting programs.
All students are welcomed to take an active part in it in the school's auditorium at 2:30pm on December 30th. Hope all the students and teachers will arrive on time.

1、满分为120分,第一环节环100分,第二环节20分；以总成绩为最后成绩.
The full score of each contestant is 120 with 100 alloted to the first round and 20 to the second.
2、第一环节原声重现注重选手的基本语言技能,具体如下：
Contestants are supposed to show their basic language skills during the first round.
a,语音语调：应使用标准英国英语或美国英语、标准日语.发音清晰,音调、音高合适,语言流利,音色优美.
a Prononciation and Intonation: Standard American or British Accent are prefered, as well as Standard Japanese. Contestants will win their scores by speaking clearly and fluently with suitable tone and pitch and beautiful voices.
b,情感表达：能够准确到位的表现出剧中人物的情感,如快乐,悲痛,忧伤等.
b Emotion Expression: Contestants should be able to show the characters' feelings such as happiness, pain and sorrow according to the plot.
c,吻合度：即与影片的台词,剧情,效果,及人物的口型一致的程度.
Matchness: Contestantes will be marked according to the matchness of their performance with the original version of the film, including lines, plots, effects.
d, 配合：即组员之间的默契,如对白的连贯性等.
d Cooperation: Contestants are expected to act coordinated, such as the fluence of lines.
3、第二环节注重选手的综合语言能力和创新能力
The second round is designed to test contestants language ability and creativity.
a, 语言表达：综合语言能力,包括语音语调,词语词组搭配,表达技巧等.
a Language expression: Contestants are judged on language abilities, including prononciation, intonation, the use of words and phrases and the ability of expressing ideas.
b, 内容创新：在原来影片的基础上的发挥程度及效果.可以自由发想象力和创意.对原有片断的新的诠释,并能达到一定的现场效果.
Creation: Contestants are encouraged to creat as they want based on the original film and are supposed to stir up some reflections of the audiences
c,情感表达：能够准确到位的表现出剧中人物的情感,如快乐,悲痛,忧伤等
C Emotion Expression: Contestants should be able to show the characters' feelings such as happiness, pain and sorrow according to the plot.
d, 配合：即组员之间的默契,如对白的连贯性等.
d Cooperation: Contestants are expected to act coordinated, such as the fluence of lines.

同学们,初三了,我们都知道 最近我们都已在备战中考了,同学们都无闲暇的时间参加校运会.
但是,请各位同学想想,初三是一个什么概念 我想同学们都会说 是冲刺中考的时候了,但是 事实不仅如此 初三 也是我们在母校最后的一年了 那么我们是否该在这难得的一年一度的盛会留下一些我们最后的美好记忆呢 好让我们中考后 彼此分道扬镳时 还保有那一份纯真、美好.同学们 ,让我们都动起来吧 去创造属于我们的印记! （其实上面哪一位仁兄说的也挺对的,我也只不过是添油加醋了点 话说我明年就初三咯 o(）＾）)o 唉）

Boys and girls,
May I have your attention, please? I have an announcement to make.
The Student Union is going to hold a party on Saturday evening, December 29, to  welcome our friends from the United States. The party will be held in the meeting hall of Science and Technology Building. It will begin at 7:00 p.m. There will be music, dancing, singing and exchange of gifts. Will everyone please bring along a small gift for this purpose.
Remember to wrap it up, sign your name and write a few words of good wishes. Don’t forget the time. There is certain to be a lot of fun. Everyone is welcome.
That’s all. Thank you.

（1）20，500（2）200，图形见解析（3）0.36


(1)∵A、B两组捐款人数的比为1∶5，B组捐款人数为100人，
∴A组捐款人数为：100÷5＝20，
A、B两组捐款人数所占的百分比的和为：1－40%－28%－8%＝1－76%＝24%，
A、B两组捐款的人数的和为：20＋100＝120，
120÷24%＝500，故答案为：20，500；
(2)500×40%＝200，C组的人数为200，
补图见图．

(3)∵D、E两组的人数和为：
500×(28%＋8%)＝180，
∴捐款数不少于30元的概率是： ＝0.36(或：28%＋8%＝36%＝0.36.)

解题思路：直接利用频数分布表中的数据和频数，频率，总数之间的关系列式求算即可；
根据样本来估计该校1800名学生中，最喜欢收看羽毛球比赛的人数为：1800×17%=306（人）．

（1）足球的频数是32，游泳的频数是12，游泳的频率是6%（或0.06），
如图：
最喜欢收看的项目 频数（人数） 频率
足球 32 16%
篮球 56 28%
排球 20 10%
羽毛球 34 17%
游泳 12 6%（2）从表格中看出：篮球最多，田径最少；
（3）该校1800名学生中，喜欢收看羽毛球比赛的人数=1800×17%=306（人）．

点评：
本题考点： 频数（率）分布表；用样本估计总体．

考点点评： 本题考查读频数分布表能力和频数与频率的求算方法以及它们之间的关系，要会用样本估计总体．利用统计图表获取信息时，必须认真观察、分析、研究统计图，才能作出正确的判断和解决问题．

Notice
Do you like basketball? Are you crazy about basketball Now it's your chance to be up close to the basketball star-YaoMing
2p.m 10.212 010 in the school meeting hall that on the third floor there will be a speech Yao will deliver a speech about the history of the basketball also according to his playing skills he will give some advice on playing basketball also he will talk about the condition on his training and tournment in the USA
what's more he will play basketball with us after the speech
So the students' union want all the students can arrive on time and keep in order
姐.我只能写到这份上了.

设：镶上的彩纸条宽为x厘米
﹙18＋2x﹚﹙12＋2x﹚=216＋144
解这个方程得：x1≈2.1，x2≈－17.1﹙不合题意，舍去﹚
镶上的彩纸条宽大约是2.1厘米

你好,同学,很高兴回答你的问题

正确答案如下；

March 12th is Tree-planting Day. On that day the Student Union will take students to plant trees on the West Mountain. We are going to get together at school gate at 7:00 a.m. Then we are going to take the school bus to get there. It will take us half an hour to get there by bus. We should be careful on the bus. We shouldn't play or fight on the bus. Every class should take some spades to dig holes and take some basins to carry water. I think it's really kind of us to plant trees.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
希望能帮到你,祝更上一层楼O(∩_∩)O
不明白请继续追问,可以详谈嘛(*^__^*)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

布置这道题的老师真的变态,不要说小学生,我是教书法的老师也花了不少时间才做完,因为这必须是小学生学过的生字,没有参考答案叫他们语文老师做也不一定做的全,这应该是书法老师上课讲解的类容,叫学生归纳真的有点难了,希望下面的答案对你有帮助.下面是手写体：

April 10
Dear student,
In order to make our students have a more colourful school life , we students' union will hold a music week in the first week in May . in the programme, you can show us your perfect sing in popular songs and alsoif you can play some classic and folk music some instrument ,which would be OK .we also have somg special competition in music,which means when you hear the song ,you should tell us which song does it come from.As for the place , you will be informed on time. If anyone is interested in it ,please sign up before April 20th
Student' Union

略

（1）③，
（2）图补充完整，
（3）根据抽查的60人中每天（除课间操外）课外锻炼平均时间不大于20分钟的人数为：10+35+10=55人，
∴该校初中三年级共有240名同学，则其中每天（除课间操外）课外锻炼平均时间不大于20分钟的人数约为：240×
55
60 =220．
故答案为：220．

Dear students,
The school had decided to organize the 8th grade students to watch the soccer match tomorrow held in the Sports Center near the school. Please get together at the school gate in the afternoon; thwn we will walk there. You may bring some drinking water as well.
Thanks

Dear students
Doyouwant to havea beautiful,clean and comfortableschool?Itto comply with theserules: Do notlitterandto protectthe classroom clean,andshall noteatin the classroom.Careofflowers and trees,instantturn off the lightsandfaucet.Recycling oftextbooks.Thegraffition the wallin the classroom,orin the classroomto loud noiseand I believeweachieve these,our schoolswillbecomemore beautiful.
Your classmates
亲爱的同学们
你们想拥有一个美丽干净舒适的学校吗?那就遵守这些规则吧：不得乱扔垃圾,保护教室清洁,不得在教室里吃东西.爱护花草树木,即时关灯及水龙头.循环使用课本.不得在教室墙上乱涂乱画,或在教室里高声喧哗. 我相信我们做到这几点,我们的学校将会变得更美丽.
你的同学
×年×月×日.

Our school students will be held on the afternoon of February 15, 2012 the activities of the campus bookstores. The purpose of this activity is to provide students an opportunity to exchange books and make better use of the borrowed books. Activities include that you do not want to keep the books to the Book Fair on the sale, purchase your favorite book and exchange of books.

10道题中随机抽取3道进行测试有120种抽法
学生抽到两道以上不会题目的抽法有22种
合格率为1-22/120=49/60

25

解题思路：（I）记至少有2人是“幸福”为事件A，利用间法和排列组合知识能求出至少有2人为“幸福”的概率．
（Ⅱ）由题意知ξ的可能取值为0，1，2，3．分别求出P（ξ=0），P（ξ=1），P（ξ=2），P（ξ=3），由此能求出ξ的分布列和数学期望．

（I）记至少有2人是“幸福”为事件A，
由题意知
P（A）=1-

C34

C316-

C24
×C112

C316
=1-[1/140]-[18/140]=[121/140]．…（6分）
（Ⅱ）由题意知ξ的可能取值为0，1，2，3．
P（ξ=0）=（[1/4]）³=[1/64]，
P（ξ=1）=
C13•
3
4•(
1
4)2=[9/64]，
P（ξ=2）=
C23(
3
4)2(
1
4)=[27/64]，
P（ξ=3）=（[3/4]）³=[27/64]，…（10分）
∴ξ的分布列为：

ξ 0 1 2 3
P [1/64] [9/64] [27/64] [27/64]Eξ=
1
64×0+
9
64×1+
27
64×2+
27
64×3=

点评：
本题考点： 离散型随机变量的期望与方差；互斥事件的概率加法公式．

考点点评： 本题考查概率的求法，考查离散型随机变量的分布列和数学期望的求法，是中档题，解题时要注意排列组合的合理运用．

下载个网易有道，马上就翻译出来了

1.他们都认为他成功的可能性很小.They all think that he stands little chance of success.2.我不知道她为何总带有一种闷闷不乐的神情.I wonder why she is taking on an air of depression all the time.3.等到所有同学都就座后,学生会主席才开始宣布野营的日程安排.It was not until all the students had taken their seats that the president of the students’ union proceeded to announce the camping itinerary.4.胃是人体至关重要的器官,请善待之.As one of the vital organs of the human body, the stomach should be taken good care of.5.他认为总经理如此重视那些日常琐事是荒唐的.He thinks that it is ridiculous for the general manager to attach so much importance to those trivial daily matters.

Nowdays,most of students think they are healthy ,so they don't like doing exerises.I will tell these students some advantages of doing exerises. At these days ,most of students pay more attentions on...

Hello everybody i wanna be a zhuxi

Dear brothers and sisters,
  Oh behalf of the University Students' Union, I, the Chairman of the Union , am earnestly calling for yo ur active participation in our environmental protection campai gn. It is the duty of every global villager； man just can not sustain his glorious c i vilization without a rewarding environment, which will be possible only if man makes considerable efforts to protect the environment.
Do you cherish precio us opportunities to volunteer in our joint efforts in environmental protection? Here is a great one not to be missed by any enthusiastic youth； Right next Saturday, our university is to run a publicity campaign to advocate environmental protection across the city. The University Students' Union will be in charge of recruitment of volunteers. Let's join our h ands and take action immediately.