抽签笔谈

金晓菁　一般意义的抽签问题是 :设有a只中签和 b只空签 ,现任意地从中一只一只无放回地抽出来 ,求第 k( 1≤ k≤ a+ b)次中签的概率 .略解　设“第 k次中签”为随机事件 B,则依题意 ,分为三个求解步骤 :(1 )求基本事件总数 n.将 a只中签和 b只空签分别均视为不同 (例如设想将其编号 ) ,并将抽出的签依次放在排成一条直线的a+ b个位置上 ,则 n等于所有可能的排法 ,即n=Aa+ba+b=( a+ b) !.( 2 )求 B包含的结果数 m.因为第 k次中签有 a种可能性 ,而所有另外 ( a+ b- 1 )次抽签 ,即 ( a+ b- 1 )个元素的全排列数为Aa+b- 1 a+b- 1 =( a+ b- 1 …     

“倒扣杯”问题解法

问题:a 只茶杯,杯口朝上,每次将其中 b 只同时翻转,称为一次运动。问,能否经过若干次运动,使茶杯杯口全部朝下?(a、b均为自然数,且 a≥b)解:分 b 为奇数和偶数两种情况:1.b 为奇数,一定可解。操作方法如下:设 a=b.q r(0≤r相似文献   

我们来画画

<正>Picture One(图一): 1)Let's draw a big head． 1)画一个大大的头; 2)Then draw two big black eyes． 2)再画两只大大的黑眼睛; 3)And draw a small mouth and nose． 3)画一张小嘴,一个小鼻子; 4)And then draw two small black ears．4)再画两个小小的黑耳朵。 What's this?This is a panda．这是什么?这是一只熊猫。     

贪婪的旅行者

Once,there was an old tiger that could no longer hunt.One morning,he stood by a lake and held a gold bracelet~2 in one paw~3.He was shouting,"Ladies and Gentlemen!A gold bracelet for my kindness."曾经一只老虎,它老了,不能抓捕猎物了。一天早上,它站在湖边,一个爪子拿着一只金手镯,喊道:"女士们,先生们,为表善意,我献出一只金手镯。"A traveler,passing by,liked the gold bracelet.However,he was scared of the tiger.一个旅行者刚好经过,他很喜欢这个金手镯,但是他怕老虎。     

形容词和副词及其比较等级

一、多个形窖词作定语时的排序问题易错笔记多个形容词修饰名词时,其顺序为:限定词一数词一描绘词一(大小,长短,形状,新旧,颜色)一出处一材料性质一类别一名词。例如:a small round table/a tall gray building/a dirty old brown shirt/a famous German medical school/an expensive Japanese sports car注意:多个形容词作定语时,形容词之间通常不用加and;但是,当这些形容词为表示同一方面的形容词时,这些形容词之间通常要加and,例如:a black and white cat(一只黑白相间的猫)。【例1】One day they crossed the____bridge behind     

用一个推广的命题证明第50届IMO第6题

题目 设a1,a2,…,an是互不相同的正整数.M是有n-1个元素的正整数集,且不含数s=a1＋a2＋…＋an.一只蚱蜢沿着实数轴从原点0开始向右跳跃n步,它的跳跃距离是a1,a2,…,an的某个排列．证明：可以选择一种排列,使得蚱蜢跳跃落下的点所表示的数都不在集合M中．     

红色的小羽毛

从前有一对夫妇,很穷,常常挨饿。那男人常常到森林里(打猎),但他不是个好猎手,有时带回家的仅是一只小鸟。1. There once lived a man and his wife. They were very poor and always hungry. The man often went to the forest, but he was a bad hunter and sometimes brought home only a small bird.一天,他又到森林里去了,但对他来说这是很糟糕的一天:他连一只小鸟也未找到。他又累又伤心,便在一棵树下坐下来休息,接着他便听见一只鸟儿动听的歌声。2.O ne day he went to the forest a-gain.But it was a very bad day for him:he di…     

Забд■дший(迷途的) зáйчик

H及。T血详夕K(灌)n卫么耳郎.Om只一八如e只oHflo JUIeCy30Kpyr,HB及Pyrc丑bll-IJHT:KTO--ToB月ecyB“及HT:a 3T()劝HtIHK MaJIeHbKHHCf’IP只Ta丑c只3a 一qT0ccocH夕。r6pbK。pb班。ePr(嚎陶大哭).T《65沂?一y八H。巨HHoe。砷,,i。、eT 6a详夕K.AT叮H叨6Ba eKa劝Tb He M6歼‘盯,B晚n卫么甘盯Hn卫么MeT.Xopotu6,B乡二龙MoeB沪M*二e帕月aM仑Mo、沪Ha,KoT6Pa只、enaceKa劝二a6a详夕Ky· OK63br助eTC只,MHoro仄HeH Ha3a八BbIUJeJI 3aH耳HK noryJI只TbB几eC H noTe一P只月c只·eHa耳么几a6石I刀0.Hy,…     

在英语教学中教师对学生的“扶助”作用

随着新课程的全面铺开．英语难教难学的现象更为突出。针对这一普遍存在的问题．笔者觉得教师应该在教学中像大人教小孩走路那样．起初给孩子一双手。搀扶其学步。后来给一只手，让其半独立走。继而放开手。鼓励其大胆地往前走。在英语教学中也来个先学走路。给学生一只手．扶助学生安全度过英语的“入门”关。在IEFC Book I Lesson 87中有句话“Can you give me a hand?”其句子的短语：“give sb．a hand”直译：给某人一只手。意译：给予……帮助。如何给学生一只手．帮助学生学好英语是个很棘手的问题。笔者在教学中做了一些探索。     

狐狸和山羊

One hot summer day, all the springs and brooks weredry. A fox felt very thirsty and wanted to have a drink.Hestole into a farmyard, but ran away quickly as soon as hecaught sight of a dog.一个炎热夏季的某一天，所有的泉和小溪都干涸了。一只狐狸感到口渴想喝水，他溜进一家农家庭院，但很快跑走了，因为他看见了一只狗。At last he saw a well and came up, but the water wasquite out of his reach.最后他看见了一口井并走了过去，但井水很深，他喝不着。He tried again and again to reach it until he suddenlyfell …     

毕飞宇:一镜、一钟、一影、一胡琴而已

本文从毕飞宇小说中一再出现的镜、钟、影和胡琴的意向入手,考察毕飞宇小说的叙述人称、叙述速度、叙述结构和叙述意图。深入阐释＂我＂与＂他＂的分离与揉合,＂快＂与＂慢＂的交替与演变,＂是＂与＂非＂的分明与模糊,＂语言＂与＂沉默＂的相反而相成。     

Toward a Profession,Not a Craft

Physical education has a rich tradition of concern for the development of fully functioning individuals, but this tradition is in danger of being marginalized by the dominant technocratic and competitive structures of today's physical education. The purpose of this paper, in seeking to readdress the value of the experiential dimensions of sport, is to provide the instructor with insight into a specific domain of sport—challenging outdoor activity, or risk sport—that holds particular value for Bain's (1988) alternative approach for humanistic physical education. Employing the model of risk-sport involvement (Robinson, 1992) as an analytical framework, the paper attempts to promote an understanding of the complex nature of the risk-sport experience and the potential value such experiences hold for personal growth, meaningful social interaction, and social change.     

强化基础 优化设置 构建研究生课程体系

通过确立“顶层设计,整体规划”的思想,对课程进行优化、整合,强调基础理论知识学习和宽口径培养,构筑起新的研究生课程体系。     

Burning,Fluttering, and Extinguishing of a Candle Flame in a Tube

In this article, we report some experimental results on the behaviour of the flame of a candle kept at the bottom of a glass tube, which is open at the top and closed at the bottom. Thus, the supply of oxygen for the continuous burning of the flame is possible only from the top open end of the tube. We find that the candle burns steadily below a critical tube height. Above this height, the flame oscillates in size, and a further increase in tube height leads to the flame extinguishing quickly.     

啸竹

啸竹始于魏晋竹林七贤，王徽之时达到高潮，唐宋还有发展。啸竹不仅在竹林场域中创造特殊的音乐享受，也在竹我的相对中将竹脱俗的气质、高洁的品性化作魏晋风流。啸竹在世界化中较为独特。     

做校长·做学问·做人

从前,有一句话,叫做"吃得苦中苦,方为人上人".这句话被认为动机不纯,怎么可以做"人上人"呢?其实,对于"人上人"可以作不同的理解,一种理解是"骑在人民头上,作威作福",这种"人上人"当然不好;但也可以解释为比别人做更多的贡献,吃更多的苦,经过更多的挫折与困难而比一般人更成熟、更坚强,更知道怎么做人.实际上,对这句话应是作后一种理解的,因为这种"人上人"是与"苦中苦"联系在一起的.     

Education,Religion, and a Sustainable Planet

Religious pluralism led to the colonies' separation of church and state by 1776, to Mann's campaign for common schooling, and to the complete secularization of public schools by 1900. The dependence of Western theology upon untenable Greek metaphysics justifies an explanation that the evolutionary purpose of religion was to promote personal integration and social cohesion. This also occurs in civic religion, herein explicated as the common faith established by truths from intersubjectively valid inquiries and by experienced qualities (i.e., the goodness) of things in the natural, societal, and lived worlds of the natural and social sciences and humanities. This promotes natural piety and a sustainable planet by grounding education in the child's being in the world. The inclusion of formal religion in the public school curriculum is considered, but unnecessary, because schools already promote individual development and social cohesion through education for citizenship, etc.     

伦敦——历史悠久的城市

It was the Romans who decided to build the city of London. They saw that a city with a bridge over the River Thames could be useful, both for traveling to Europe and for traveling in England. The Guil...