克莱因瓶是一个不可定向的二维紧流形，而球面或轮胎面是可 克莱因瓶 克莱因瓶 定向的二维紧流形。如果观察克莱因瓶，有一点似乎令人困惑－－克莱因瓶的瓶颈和瓶身是相交的，换句话说，瓶颈上的某些点和瓶壁上的某些点占据了三维空间中的同一个位置。我们非常接近地球，目前国 AT this unexpected announcement Martin exchanged a swift glance with Corinna. She smiled, drew a five franc piece from her purse and laid it on the table. Martin, wondering, did the same. The Marchand de Bonheur unbuttoned his frock coat and slipped the coins, with a professional air, into his waistcoat pocket. “Mr. Overshaw,” said he, “you must understand, as our charming friend Corinna Hastings and indeed half the Quartier Latin understand, that for such ha0千米至30千米的浓硫酸云，地面温度从不低于400℃，是个名副其实的“炼狱”般世界。金星地面的大气压强为地球的90倍，相当于地球海洋中900米深度时的压强。金星大气主要由二氧化碳等温室气体组成，失控的温室效应，是导致金星极端气候的主要原因。由于金星没有内禀磁层保护，诱发磁层中磁场重联释放的巨大能量，使得金星大气被加热后加速逃逸。科学界认为，金星上大气的逃逸，是造成金星上缺水而被富含二氧化碳的稠密大气所笼罩，从而导致严重的温室效应的原因。[44] 木星是离太阳第五颗行星，而且是最大的一颗，比所有其他的行星 木星及其卫星欧罗巴（木卫二） 木星及其卫星欧罗巴（木卫二） [45] 的合质量大2倍（地球的318倍），直径142987km。它是气态行星没有实体表面，由90%的氢和10%的氦（原子数之比, 75/25%的质量比）及微量的甲烷、水、氨水和“石头”组成。这与形成整个太阳系的原始的太阳系星云的组成十分相似。木星可能有一个石质的内核，相当于10－15个地球的质量。内核上则是大部分的行星物质集结地，以液态氢的形式存在。液态金属氢由离子化的质子与电子组成（类似于太阳的内部，不过温度低多了）。木星共有67颗木卫。按距离木星中心由近及远的次序为：木卫十六、木卫十四、木卫五、木卫十五、木卫一、木卫二、木卫三、木卫四、木卫十三、木卫六、木卫十、木卫七、木卫十二、木卫十一、木卫八和木卫九。[46] 水星是最接近太阳的行星。水星的半径约为2440公里，在八大行星中是最小的。水星昼夜温差极大，白天摄氏 430 度，晚上约可达零下170 度，是太阳系八大行星中温差最大的一个行星。[47]  水星的外大气层非常稀薄，是由水星表面和太阳风中的原子和离子构成。[48]  科学家确认水星表面含有丰富的碳，认为碳是水星表面呈黑色的原因，水星表面的岩石是由低重量百分比的石墨碳构成。[49] “好奇号”火星探测器在火星表面采集样本 “好奇号”火星探测器在火星表面采集样本 [50] 火星是地球的近邻，是太阳系由内往外数第四颗行星。直径6794km，体积为地球的15%，质量为地球的11%。火星表面是一个荒凉的世界，空气中二氧化碳占了95%。火星大气十分稀薄，密度还不到地球大气的1%，因而根本无法保存热量。这导致火星表面温度极低，很少超过0℃，在夜晚，最低温度则可达到-123℃。火星被称为红色的行星，这是因为它表面布满了氧化物，因而呈现出铁锈红色。其表面的大部分地区都是含有大量的红色氧化物的大沙漠，还有赭色的砾石地和凝固的熔岩流。火星上常常有猛烈的大风，大风扬起沙尘能形成可以覆盖火星全球的特大型沙尘暴。每次沙尘暴可持续数个星期。火星两极的冰冠和火星大气中含有水份。从火星表面获得的探测数据证明，在远古时期，火星曾经有过液态的水，而且水量特别大。[51] 土星是离太阳第六颗行星，直径120536┪，体积仅次于木星。主要由氢组成，还有少量的氦与微量元素，内部的核心包括岩石和冰，外围由数层金属氢和气体包裹着。地球距离土星13亿公里。土星的引力比地球强2.5倍，能够牵引太阳系内其它行星，使地球处于一个椭圆轨道中运行，并且与太阳保持适当距离，适宜生命繁衍。当土星轨道倾斜20度将使地球轨道比金星轨道更接近太阳，同时，这将导致火星完全离开太阳系。[52]  土星是已知唯一密度小于水的行星，假如能够将土星放入一个巨大的浴池之中，它将可以漂浮起来。土星有一个巨大的磁气圈和一个狂风肆虐的大气层，赤道附近的风速可达1800千米/时。在环绕土星运行的31颗卫星中间，土卫六是最大的一颗，比水星和月球还大，也是太阳系中唯一拥有浓厚大气层的卫星。[53] 天王星是离太阳第七颗行星，51118km。体积约为地球的65倍，在九大行星中仅次于木星和土星。天王星的大气层中83%是氢，15%为氦，2%为甲烷以及少量的乙炔和碳氢化合物。上层大气层的甲烷吸收红光，使天王星呈现蓝绿色。大气在固定纬度集结成云层，类似于木星和土星在纬线上鲜艳的条状色带。天王星云层的平均温度为零克莱因瓶是一个不可定向的二维紧流形，而球面或轮胎面是可 克莱因瓶 克莱因瓶 定向的二维紧流形。如果观察克莱因瓶，有一点似乎令人困惑－－克莱因瓶的瓶颈和瓶身是相交的，换句话说，瓶颈上的某些点和瓶壁上的某些点占据了三维空间中的同一个位置。我们非常接近地球，目前国 AT this unexpected announcement Martin exchanged a swift glance with Corinna. She smiled, drew a five franc piece from her purse and laid it on the table. Martin, wondering, did the same. The Marchand de Bonheur unbuttoned his frock coat and slipped the coins, me? I tell you now. I am sending you to her—she is twenty—and to my excellent brother-in-law Bigourdin, because I think you are good children, and I should like to give you a bit of my heart for my ten francs.” “Fortinbras,” said Corinna, with a quick outstretch of her arm, “I’m a beast. Tell me, what is she like?” “To me,” smiled Fortinbras, “she is like one of the wild flowers from which Alpine honey is made. To other people she is doubtless a well-mannered commonplace young person. You will see her and judge for yourselves.” “How far is it from Paris to Brant?me?” asked Martin. “Roughly about five hundred kilometres—under three hundred miles. Take your time. You have sixty pounds’ worth of sunny hours before you—and there is much to be learned in three hundred miles of France. In a few weeks’ time I will join you at Brant?me—journeying by train as befits my soberer age—I go there a certain number of times a year to see Félise. Then, if you will continue to favour me with your patronage, we shall have another consultation.” There was a brief silence. Fortinbras looked from one young face to the other. Then he brought his hands down with a soft thump on the table. “You hesitate?” he cried indignantly. “You’re afraid to take your poor, little lives in your hands even for a few weeks?” He pushed back his chair and rose and swept a banning gesture, “I have nothing more to do with you. For profitless advice my conscience allows me to charge nothing.” He tore open his frock coat and his fingers diving into his waistcoat pocket brought forth and threw down the two five-franc pieces. “Go your ways,” said he. At this dramatic moment both the young people sprang protesting to their feet. “What are you talking about? We’re going to Brant?me,” cried Corinna, gripping the lapels of his coat. “Of course we are,” exclaimed Martin, scared at the prospect of losing the inspired counsellor. “Then why aren’t you more enthusiastic?” asked Fortinbras. “But we are enthusiastic,” Corinna declared. “We’ll start to-morrow,” said Martin. “At six o’clock in the morning,” said Corinna. “At five, if you like,” said Martin. Fortinbras embraced them both in a capacious smile, as he deliberately repocketed the coins. “That is well, my children. But don’t do too many unaccustomed things at once. In the Dordogne you can rise at five—with enjoyment and impunity. In Paris, your meeting at that hour would be fraught with mutual antipathy, and you would not find a shop open where you could hire or buy your bicycles.” “I’ve got one,” said Corinna. “So have I,” said Martin; “but it’s in London.” Fortinbras extra knows that she can entrust her happiness to my hands. And Lucien is a capital fellow. They will be very happy.” Thus he warned a sensitive Martin off philandering paths, and, with his French adroitness, separated youth and maiden as much as possible. And this was not difficult. You see Félise acted as manageress in the H?tel des Grottes, and her activities were innumerable. There was the kitchen to be ruled, an eye to be kept on the handle of the basket—if it danced too much, according to the French phrase, the cook was exceeding her commission of a sou in the franc; there were the bedrooms and clean dry linen to be seen to, and the doings of Polydore, the unclean, and of Baptiste, the haphazard, to be watched; there were daily bills to be made out, accounts to be balanced, impatient bagmen to be cajoled or rebuked; orders for paté de foie gras and truffles to be despatched—the H?tel des Grottes had a famous manufactory of these delights and during autumn and winter supported a hive of workers and the shelves in the cool store-house were filled with appetising jars; and then the laundry and the mending and the polishing of the famous bathroom—ma foi, there was enough to keep one small manageress busy. Like a bon h?telier, Bigourdin himself supervised all these important matters, ordering and controlling, as an administrator, but Félise was the executive. And like an obedient and happy little executive Félise did not notice a subtle increase in her duties. Nor did Martin, honest soul, in whose eyes a betrothed maiden was as sacred as a married woman, remark any change in facilities of intercourse. For him she flashed, a gracious figure, across the half real tapestry of his present life. A kindly word, a smiling glance, on passing, sufficed for the maintenance of his pleasant understanding with Félise. For fe中的同一个位置。我们可以把克莱因瓶放在四维空间中理解：克莱因瓶是一个在四维空间中才可能真正表现出来的曲面。如果我们一定要把它表现在我们生活的 对他国的影响 在教会严密控制下的中世纪，也发生过轰轰烈烈的宗教革命。因为天主教的很多教义不符合圣经的教诲，而加入了太多教皇的个人意志以及各类神学家的自身成果，所以很多信徒开始质疑天主教的教义和组织，发起回归圣经的行动来。捷克的爱国主义者、布拉格大学校长扬·胡斯（1369～1415年）在君士坦丁堡的宗教会议上公开谴责德意志封建主与天主教会对捷克的压迫和剥削。他虽然被反动教会处以火刑，但他的革命活动在社会上引起了强烈的反应。捷克农民在胡斯党人的旗帜下举行起义，这次运动也波及波兰。1517年，在德国，马丁·路德（1483～1546年）反对教会贩卖赎罪符，与罗马教皇公开决裂。1521年，路德又在沃尔姆国会上揭露罗马教廷的罪恶，并提出建立基督教新教的主张。新教的教义得到许多国家的支持，波兰也深受影响cted from his person a dim, chainless watch. “It is now a quarter past one. Time for honest folk to be abed. Meet me here at eleven o’clock to-morrow, booted and spurred, with but a scrip at the back of your bicycles, and I will hand you letters to Félise and the poetic and philosophic Bigourdin, and now,” said he, “with your permission, I will ring for Auguste.” Auguste appeared and Martin, waving aside the protests of Corinna, paid the modest bill. In the airless street Fortinbras bade them an impressive good night and disappeared in the byways of the sultry city. Martin accompanied Corinna to the gaunt neighbouring building wherein her eyrie was situate. Both were tongue-tied, shy, embarrassed by the prospect of the intimate adventure to which they had pledged themselves. When the great door, swung open by the hidden concierge, at Corinna’s ring, invited her entrance, they shook hands perfunctorily.际天文学界普遍认为此距离在100光年以内，它就能够对地球的生物圈产生明显的影响，这样的超新星被称为近地超新星。有研究认为，在地球历史上的奥陶纪大灭绝，就是一颗近地超新星引起的，这次灭绝导致当时地球近60%的海洋生物消失。with a professional air, into his waistcoat pocket. “Mr. Overshaw,” said he, “you must understand, as our charming friend Corinna Hastings and indeed half the Quartier Latin understand, that for such happiness as it may be myIt is one of the many mind-wrecking institutions of which our beloved country is so proud.” “I’m glad to hear you say that,” cried Martin. “I’ve been helping to wreck minds there for the last ten years. I’ve taught French. Not the French language; but examination French. When the son of a greengrocer wants to get a boy-clerkship in the Civil Service can drink all that syrup without being sick I can’t understand,” she remarked. “Omnicomprehension is not vouchsafed even to the very young and innocent, my dear,” said Fortinbras. Martin glanced across the table apprehensively. If ever young woman had been set down that young woman was Corinna Hastings. He feared explosion, annihilation of the down-setter. Nothing of the sort happened. Corinna accepted the rebuff with the meekness of a school-girl and sniffed when Fortinbras was not looking. Again Martin was puzzled, unable to divest himself of his old conception of Corinna. She was Corinna, chartered libertine of the land of Rodolfe, Marcel, Schaunard—he had few impressions of the Quartier Latin later than Henri Murger—and her utterances no matter how illogical were derived from godlike inspiration. He hung on her lips for some inspired and vehement rejoinder to the rebuke of Fortinbras. When none came he realised that in the seedily dressed and now profusely perspiring Marchand de Bonheur she had met an acknowledged master. Who Fortinbras was, whence his origin, what his character and social status, how, save by the precarious methods to which he had alluded, he earned his livelihood, Martin had，五味杂陈齐齐裹着酸楚涌上心头。迫于无奈，甘伯父成了铁原英雄们的送终人；32年后的今天，我们依然要迫于无奈成为4、5连兄弟们的送终人……这是何种滋味？祖国与人民给我们创造的条件不知比我们的父辈强上多少倍，我们所要面对的敌人不知道比我们的父辈所要面对的不知弱上多少倍。作为祖国与人民的守护者，作为光荣的八一军旗继任者，我们怎么能在这样的条件，以这样的方式延续着父辈悲怆的光荣传统？就像老甘哭嚎的，比起我们的父辈，我们这TM打的是啥仗？我们都TM是没卵的孬种！　　央视版水浒中的公孙胜 央视版水浒中的公孙胜(14张) 宋江攻打高唐州，却败于太守高廉的妖法。吴用让戴宗去蓟州寻取公孙胜，李逵也随同前往。二人在蓟州机缘巧合遇到公孙胜的邻居，得知公孙胜居住在九宫县二仙山。戴宗赶赴二仙山，让李逵假意伤害公孙胜的母亲，将公孙胜激出相见。但公孙胜却不肯出山，称师傅罗真人不肯相放。戴宗苦苦哀告，又去拜见罗真人，请他放公孙胜下山。[3] 罗真人传授公孙胜计算机（computer）俗称电脑，是现代一种用于高速计算的电子计算机器，可以进行数值计算，又可以进行逻辑计算，还具有存储记忆功能。是能够按照程序运行，自动、高速处理海量数据的现代化智能电子设备。由硬件系统和软件系统所组成，没有安装任何软件的计算机称为裸机。可分为超级计算机、工业控制计算机、网络计算机、个人计算机、嵌入式计算机五类，较先进的计算机有生物计算机、光子计算机、量子计算机等。计算机发明者约翰·冯·诺依曼。计算机是20世纪最先进的科学技术发明之一，对人类的生产活动和社会活动产生了极其重要的影响，并以强大的生命力飞速发展。它的应用领域从最初的军事科研应用扩展到社会的各个领域，已形成了规模巨大的计算机产业，带动了全球范围的技术进步，由此引发了深刻的社会变革，计算机已遍及一般学校、企事业单位，进入寻常百姓家，成为信息社会中必不可少的工具。计算机的应用在中国越科比·布莱恩特（Kobe Bryant），1978年8月23日出生于美国宾夕法尼亚州费城，前美国职业篮球运动员，司职得分后卫/小前锋（锋卫摇摆人），绰号“黑曼巴”/“小飞侠”。[1]  1996年第1轮第13位被夏洛特黄蜂队选中，后来被交易到湖人队。整个NBA生涯（1996年-2016年）全部效力于NBA洛杉矶湖人队，是前NBA球员乔·布莱恩特的儿子 [1]  。科比是NBA最好的得分手之一，生涯赢得无数奖项 [1]  ，突破、投篮、罚球、三分球他都驾轻就熟，几乎没有进攻盲区，单场比赛81分的个人纪录就有力地证明了这一点。除了疯狂的得分外，科比的组织能力也很出众，经常担任球队进攻的第一发起人。另外科比还是联盟中最好的防守人之一，贴身防守非常具有压迫性。2016年4月14日，科比·布莱恩特在生涯最后一场主场对阵爵士的常规赛后宣布退役。[1]  2017年12月19日，湖人主场对阵勇士，中场时刻为科比的8号和24号2件球衣举行了退役仪式。[2]  2018年3月13日，科比凭借和动画师格兰·基恩合作的短片《亲爱的篮球》获得第90届奥斯卡最佳短片奖。[3] 来越普遍，1989-90赛季揭幕前，公牛队请来了菲尔·杰克逊。在“禅师”杰克逊的指教下，公牛引进三角进攻。这个赛季，公牛55胜27负，创1971-72赛季以来队史最佳战绩。乔丹在和骑士的比赛中创造生涯最高得分69分。不过在1990年东部决赛中，公牛在七场鏖战中仍然输给了活塞。[7] 第一个三连冠 1991—1993年第一次三连冠 1991—1993年第一次三连冠(10张) 1990-91赛季，乔丹率领公牛一路高歌猛进，整个季后赛仅仅输了两场，乔丹率领公牛第一次夺得总冠军。这其中包括在东部决赛中横扫活塞报了一箭之仇，在总决赛主场先负一局的情况下直落四局击败湖人夺冠。乔丹场均得到31.4分、6.4个篮板、8.4次助攻，并捧起了他六个NBA总决赛最有价值球员奖杯中的第一个。[12] 1991-92赛季，乔丹场均得到30.1分，连续第2年同时获得常规赛MVP和总决赛MVP称号。季后赛首轮迎战迈阿密热队，乔丹场均45分，率领球队以3比0的总比分横扫对手。这个赛季乔丹再次率领芝加哥公牛夺得了总冠军。[1] 1993年，乔丹带领公牛在五次季后赛中四次战胜帕特里克·尤因率领的纽约尼克斯。在关键的第五场，乔丹打出了“三双”表现：29分、10个篮板和14次助攻。随后，公牛在六场内过关。在总决赛，乔丹在面对菲尼克斯太阳的六场比赛中创造了一项纪录：他场均得到了41.0分，成功夺得三连冠 [7] 然而三连冠的喜悦没多久，乔丹就接到噩耗：他的父亲被谋杀。就在新赛季训练营开始前的10月6日 [7]  ，乔丹宣布退役，并准备开始棒球生涯。棒球是父亲从小激励他从事的运动，乔丹也最终加盟了美国职棒联盟。事实上，他在棒球场上并不太成功。[7]  第二个三连冠 1996—1998年第二次三连冠 1996—1998年第二次三连冠(7张) 在1994-95赛季末期，乔丹说出了那句著名的“I'm Back”。重回NBA的乔丹在17场常规赛中，场均得到26.9分，公牛的对应战绩为13胜4负。季后赛，乔丹场均31.5分，不过公牛仍输给了拥有沙奎尔·奥尼尔的奥兰多魔术。[7] no idea; but he suddenly conceived an immense respect for Fortinbras. The man hovered over both of them on a higher plane of wisdom. From his kind eyes (to Martin’s simple fancy) beamed uncanny power. He assumed the semblance of an odd sort of god indigenous to this Paris wonderworld. Fortinbras lit another of Martin’s Virginian cigarettes—the little tin box lay open on the table—and leaned back in his chair. “My young friends,” said he, “you have each put before me the circumstances which have made you respectively despair of finding happiness both in the immediate and the distant future. Now as Montaigne says—an author whom I would recommend to you for the edification of your happily remote middle-age, having myself found infinite consolation in his sagacity—as Montaigne says: ‘Men are tormented by the ideas they have concerning things, and not by the things themselves.’ The wise man therefore—the general term, my dear Corinna, includes women—is he who has learned to face things themselves after having dispelled the bogies of his ideas concerning them. It is on this basis that I am about to deliver the judgment for which I have duly received my fee of ten francs.” He moistened his lips with the pink syrup. For the picture you can imagine a grey old lion eating ice-cream. “You, Corinna,” he continued, “belong to the new race of women whose claims on life far exceed their justification. You have as assets youth, a modicum of beauty, a bright intelligence and a stiff little character. But, as you rightly say, you are capable of nothing in the steep range of human effort from painting a picture to washing a baby. Were you not temperamentally puritanical and intellectually obsessed by the mo下193摄氏度。质量为8.6810±13×102?kg，相当于地球质量的14.63倍。密度较小，只有1.24克/立方厘米，为海王星密度值的74.7%。[54] 恒星哥白尼在他的《天体运行论》一书中认为天体运动必须满足以下七点：地心说是长期盛行于古代欧洲的宇宙学说。它最初由古希腊学者欧多克斯（提出“同心球”模型）提出，后经亚里士多德、托勒密进一步发展而逐渐建立和完善起来。托勒密认为，地球处于宇宙中心静止不动。从地球向外，依次有月球、水星、金星、太阳、火星、木星和土星，在各自的圆轨道上绕地球运转。其中，行星的运动要比太阳、月球复杂些：行星在本轮上运动，而本轮又沿均轮绕地运行。在太阳、月球行星之外，是镶嵌着所有恒星的天球——恒星天。再外面，是推动天体运动的原动天。地心说是世界上第一个行星体系模型。尽管它把地球当作宇宙中心是错误的，然而它的历史功绩不应抹杀。地心说承认地球是“球形”的，并把行星从恒星中区别出来，着眼于探索和揭示行星的运动规律，这标志着人类对宇宙认识的一大进步。地心说最重要的成就是运用数学计算行星的运行，托勒密还第一次提出“运行轨道”的概念，设计出了一个本轮均轮模型。按照这个模型，人们能够对行星的运动进行定量计算，推测行星所在的位置，这是一个了不起的创造。在一定时期里，依据这个模型可以在一定程度上正确地预测天象，因而在生产实践中也起过一定的作用。地心说中的本轮均轮模型，毕竟是托勒密根据有限的观察资料拼凑出来的，他是通过人为地规定本轮、均轮的大小及行星运行速度，才使这个模型和实测结果取得一致。但是，到了中世纪后期，随着观察仪器的不断改进，行星位置和运动的测量越来越精确，观测到的行星实际位置同这个模型的计算结果的偏差，就逐渐显露出来了。但是，信奉地心说的人们并没有认识到这是由于地心说本身的错误造成的，却用增加本轮的办法来补救地心说。当初这种办法还能勉强应付，后来小本轮增加到80多个，但仍不能满意地计算出行星的准确位置。这不能不使人怀疑地心说的正确性了。到了16世纪，哥白尼在持日心地动观的古希腊先辈和同时代学者的基础上，终于创立了“日心说”。从此，地心说便逐渐被淘汰了。简单的说,“地心说”就是以地球为宇宙的中心,“日心说”是以太阳为宇宙的中心。创立编辑 哥白尼提出 哥白尼想知道在另一个运行着的行星上观察这些行星的运行情况会是什么样的。基于这种设想，哥白尼萌发了一个念头：假如地球在运行中，那么这些行星的运行看上去会是什么情况呢？这一设想在他脑海里变得清晰起来了。一年里，哥白尼在不同的时间、不同的距离从地球上观察行星，每一个行星的情况都不相同，这是他意识到地球不可能位于星星轨道的中心。经过20年的观测，哥白尼发现唯独太阳的周年变化不明显。这意味着地球和太阳的距离始终没有改变。如果地球不是宇宙的中心，那么宇宙的中心就是太阳the circumstances which have made you respectively despair the immortal work and laid it down, disconcerted both by the archaicaced them both in a capacious smile, as he deliberately repocketed the coins. “That is well, my children. But don’t do too many unaccustomed things at once. In the Dordogne you can rise at five—with enjoyment and impunity. In Paris, your meeting at that hour would be fraught with mutual antipathy, and you would not find a shop open where you could hire or buy your bicycles.” “I’ve got one,” said Corinna. “So have I,” said Martin; “but it’s in London.” Fortinbras extracted from his person a dim, chainless watch. “It is now a quarter past one. Time for honest folk to be abed. Meet me here at eleven o’clock to-morrow, booted and spurred, with but a scrip at the back of your bicycles, and I will hand you letters to Félise and the poetic and philosophic Bigourdin, and now,” said he, “with your permission, I will ring for Auguste.” Auguste appeared and Martin, waving aside the protests of Corinna, paid the modest bill. In the airless street Fortinbras bade them an impressive good night and disappeared in the byways of the sultry city. Martin accompanied Corinna to the gaunt neighbouring building wherein her eyrie was situate. Both were tongue-tied, shy, embarrassed by the prospect of the intimate adventure to which they had pledged themselves. When the great door, swung open by the hidden concierge, at Corinna’s ring, invited her entrance, they shook hands perfunctorily.际天文学界普遍认为此距离在100光年以内，它就能够对地球的生物圈产生明显的影响，这样的超新星被称为近地超新星。有研究认为，在地球历史上的奥陶纪大灭绝，就是一颗近地超新星引起的，这次灭绝导致当时地球近60%的海洋生物消失。[78]

克莱因瓶是一个不可定向的二维紧流形，而球面或轮胎面是可 克莱因瓶 克