s与m的故事

s与m的故事篇一

S与M型等电位连接

信息系统的S型及M 型等电位连接技术探讨

来源： | 作者：孙丹波 赵连义 | 发布时间：2008-11-13 15:08:17 | 浏览：1125次【 字体：大 中 小】

摘 要 阐述在TN—s和TN—c—s接地型式中，信息系统只宜采用s型等电位连接，且要做好三相用电平衡，减少零地漂移电压，而不适宜采取M型等电位连接措施。只有在1Tr和IT供电系统中，信息系统才既可以采用s型也可以采用M型等电位连接。

关键词 s型等电位连接M型等电位连接 漂移电压

等电位连接技术已纳入我国一系列新颁布的强制性国标中，这对推动我国电气技术的发展、保证国家财产和人民生命的安全具有积极作用。笔者通过近几年大量的信息机房防雷工程实践，总结国内外有关专家的最新观点，对等电位连接技术有了一些粗浅的认识，希望能与广大工程技术人员探讨。

1 信息设备受干扰的原因

信息设备在正常工作过程中必须具备一个稳定的基准参考电位。信息设备所受干扰有两种，一是低频干扰，二是高频干扰。低频干扰主要表现为共阻抗耦合形成的干扰，由于各设备的接地点不同，地线中有电流流过时，造成各设备接地点的电位不同，从而形成干扰。具体分析可参见图1。图1中由于低频电流在接地平面内流动，设备的接地点A、B、c间有电位差，从而对信息设备形成干扰。为了消除共阻抗耦合，许多规范、规程中要求设备采用一点接地。也即是S型接地。

还有一种低频干扰主要表现为地电位抬升，如三相用电不平衡、零线重复接地、机壳漏电等形成的干扰。目前，大部分信息设备如微机等其工作接地与保护接地在机壳内已连在一起，最后经电源系统的PE线引至大地，如果PE线上有干扰电压该干扰电压会直接加到计算机的逻辑低电平上，造成整个系统的误码或信号中断。为了消除干扰，基本上都是要求处理好三相用电平衡，或者设备单独接地。

高频干扰表现在当信号或电磁干扰的频率相当高或采用快速逻辑时，如果接地线过长，由于分布电感、分布电容及引线电阻的影响导致各设备接地点的电位不尽相同，从而形成高频干扰，如图2所示。图2中设备的A点、B点、c点间有一定的电位差。虽然它们在O点的电

位是相同的。为了消除高频干扰，要求信息设备的接地线尽可能短，为此各设备需采用多点接地，也即是M型接地。

2 采用等电位措施后。TN—s、TN—c—s电源系统对信息设备造成的干扰

目前，采用比较多的电源系统主要为TN—s、TN—c—s及1Tr系统，也有少量场合采用IT及TN—c系统。规范中大多要求采用TN—s、TN—c—s系统，有的观点认为，在TN—s、TN—c—s系统中只有N线带电，而PE线不带电。笔者认为这是不正确的，正确的说法应该是N线带电流，PE线不带电流，但是PE线与N线相对大地都带有一定的电压。

在TN—s、TN—c—s系统中， 由于三相用电不平衡而造成N线中有电流流过，N线与大地之间存在接地电阻。这样，入地点O处与真正的大地间必有一定的电位差。也就是说，O点带有一定的电压，此电压也就是PE线带的电压。如果PE线直接与信息设备相连而不形成其他接地回路，则PE线上不会有电流流过。但是一旦PE线参与等电位连接，比如与结构主钢筋相连，由于PE线上的电位高于大地电位，会有电流沿PE线经结构钢筋流入建筑物的基础地网。而目前的规范上恰恰又要求PE线应参与等电位连接。

如果信息设备采用s型接法与PE线相连(单点接地)，由于设备所有接地点都通过一点入地，即使PE线上有电流，也不会产生共阻抗耦合，如图3所示。图3中虽然消除了共阻抗耦合，但由于PE线上带有电压，此电压会影响设备的信号地(直流地、逻辑地)。为此应尽量做到三相用电平衡，减少零地漂移电压(一般要求小于2V)，使PE线上电位降低。

M型接地一般做法：在机房内，从建筑物的结构主钢筋中大约每隔5m引出一等电位连接板，然后利用镀锌扁钢或铜带绕机房四周一圈，并与结构主钢筋中的等电位连接板连接，形成等电位母排。继之以网格状铜排或利用静电地板的金属支架与母排相连，形成等电位接地平面。机房内的所有金属构件均与此等电位接地平面相连，信息设备的工作地线、保护地线也以最短的距离与之相连，形成多点接地。当然，PE线也必须参与等电位连接。如前所述， 由于PE线上带有电位，必有电源经PE线流入等电位接地平面，然后通过法拉第笼式结构钢筋网入地。图4中等电位接地平面上出现了工频

电流，导致各设备的接地点电位不一致而引起干扰。

3 ，ITI(或IrI)系统信息设备可进行S型或M型等电位连接

如何消除由共阻抗耦合和地电位升高引起的低频干扰呢?笔者认为采用，ITI’供电系统可解决这一问题(由于IT系统只在少数的特殊场合使用。在此不做赘述)。，ITI’系统中PE线与N线是真正分开的，PE线中既没有电流也没有对地电压，可以说是完全干净的。PE线以任何方式与建筑物结构钢筋或信息系统的等电位接地平面相连，都不会产生干扰电流。 目前，几乎所有的机房为避免雷电或强电的干扰，均于室外设置单独接地，对信息设备而言无意中已形成，ITI’系统。此时只要电源N线不与建筑物钢筋

等金属构件相连，信息设备就可以随意进行S型及M型等电位连接。

为了最大程度地降低高频干扰，信息机房最好采用M型等电位连接，并形成网格等电位接地平面，这样可使各设备的地线最短。同时，在发生雷电等强电磁场干扰时，接地金属网格可起到衰减环路的作用，即网格中心没有电流，只在四周环形连接带上有电流存在。所以，各设备的地线最好垂直接在M型网格的中间部位，而不接在四周的环形母排上。

4结论

现阶段信息系统的接地方式不一。除规范中已不建议采用的单独接地外，有人过分强调一点

接地；有人强调共网不共线，且强弱电地线要分开一定的距离；还有人把强电地与弱电地之间用电涌保护器相连，以求雷击时导通，实现共地，而平时断开，使信息设备免受干扰。笔者认为上述做法皆有一定的缺陷。而应做到：

a．电源系统为TN-S、TN-C-S的信息设备不宜采用M型等电位连接，只宜采用S型等电位连接，且要做好三相用电平衡，减少零地漂移电压。

b．当电源系统为，ITI’(或IrI’)时，信息设备既可采用M型等电位连接，也可采用S型等电位连接。从减少高频干扰的角度看，宜采用M型等电位连接，地线垂直接在网格型等电位平面的中间部位

s与m的故事篇二

我和书的故事

我和书的故事

书，自古以来被人们称为“进步的阶梯”、“知识的源泉”、“人类文明的长生果”„„那么，我和书的故事又会是怎么样的呢？

我看书的范围很广，天文地理、童话故事、学习辅导等等的书我都喜欢看。看书也让我明白了不少道理：《窗边的小豆豆》。这本书主要讲述了作者从一个在别人眼中是“怪怪”的孩子，经过了新学校的校长的爱护和关心下，逐渐成为了一个让人们都能接受的孩子；二、《米粒上的花朵》。这本书写了很多篇散文、童话以及讲述道理的故事，这本书让我明白了很多道理；三、《快乐精灵》。这本书主要讲述了一个名叫罗小卜的孩子，把自己的快乐卖给了一只毛毛虫，从此，他成为了一个拥有一切却不会快乐的人。后来，他看见了会走的大榕树、认识了精灵谷的精灵„„后来，终于把他自己的快乐找了回来。从这本书中，我明白了一个道理：快乐虽然不能吃、不能喝、不能换来钱，但是快乐却很重要，不，可以说是极端重要。

怎么样，听了我和书的故事，我也想听听你和书的故事哦！

五年级:黄诗雅

s与m的故事篇三

子路借米孝敬父母的故事

子路借米的故事

中国有句古语：“百善孝为先”。意思是说，孝敬父母是各种美德中占第一位的。一个人如果都不知道孝敬父母，就很难想象他会热爱祖国和人民。

子路，春秋末鲁国人。在孔子的弟子中以政事著称。尤其以勇敢闻名。但子路小的时候家里很穷，长年靠吃粗粮野菜等度日。

有一次，年老的父母想吃米饭，可是家里一点米也没有，怎么办？子路想到要是翻过几道山到亲戚家借点米，不就可以满足父母的这点要求了吗？

于是，小小的子路翻山越岭走了十几里路，从亲戚家背回了一小袋米，看到父母吃上了香喷喷的米饭，子路忘记了疲劳。邻居们都夸子路是一个勇敢孝顺的好孩子。

感恩父母

女： 有一个词语最亲切，

男：有一声呼唤最动听

女：有一个人最要感谢

男：有一种人最应感恩

女：她就是——“母亲”

男：他就是——“父亲”

女：妈妈的手粗了，她把温柔的抚触给了我

男：爸爸的腰弯了，他把挺直的脊梁给了我

女：妈妈的双眼花了，她把明亮的双眸给了我 男：爸爸的皱纹深了，他把美丽的青春给了我

女：聆听妈妈殷切的话语

男：面对爸爸深沉的目光

女：我们早已习惯了这种关爱，并且认为是理所当然。 男：渐渐忘记了感动，忘了说声谢谢。

合：父母的爱像一杯浓茶，需要我们细细品味。 女：如果说母爱是船，载着我们从少年走向成熟;

男：那么父爱就是一片海，给了我们一个幸福的港湾。 女：如果母亲的真情，点燃了我们心中的希望; 男：那么父亲的厚爱，将是鼓起我们远航的风帆。 合：所有的恩情我们将铭记于心

让我们一起说声——“谢谢你们，爸爸妈妈！”

s与m的故事篇四

《数学的思维方式与创新》公开课全部作业答案分章节(一)到(三十)

还是和上个学期一样，我做过的作业都留存一份答案。《数学的思维方式与创新》这门课不知道该怎么定义，出于爱好，我自己还是把它归类为科技史的方面。其实有一定的启发作用可是内容实在太多，楼主自己都来不及。

当黑板上写着写着就把费马小定理给证了的时候，楼主内心的草泥马那个奔腾咆哮啊啊啊。 好了，下面是一到三十楼主碰到的所有题目以及正确答案。

我同时放了一份在我的豆瓣。

数学的思维方式过程一般包括？

观察-抽象-探索-猜测-论证

黎曼几何属于非欧几里得几何，并且认为过直线外一点有多少直线与已知直线平行？ 没有直线

数学的整数集合用什么字母表示？

Z

如果s、m分别是两个集合，s*m{（a，b）|a∈s，b∈m}称为s与m的什么？

笛卡儿积

将日期集合里星期一到星期日的七个集合并集能得到什么集合？

整数集

A={1，2}，B={3，4}，A∩B=？

Φ

等价关系具有的性质不包括？

反对称性

集合的不相等的子集的交集是？

空集

集合的性质不包括？

封闭性

星期三和星期六所代表的集合的交集是什么？

空集

元素与集合间的关系是？

属于关系

整数的四则运算不保“模m同余”的是？

除法

a与b被m除后余数相同的等价关系式是什么？

a-b是m的整数倍

在Zm中规定如果a与b等价类相等，c与d等价类相等，则可以推出什么相等？ a+b与c+d等价类相等

对任何a属于A，A上的等价关系R的等价类[a]R为？{s与m的故事}.

非空集

在Z7种，4的等价类和6的等价类的和几的等价类相等？

3的等价类

设A为3元集合，B为4元集合，则A到B的二元关系有几个？

12

在整数环中只有哪几个是可逆元？

-1、1

设R是有单位元e的环，a∈R，有（-e）*a=

-a

集合S上的一个什么运算是S*S到S的一个映射

二元代数运算

设R是一个环，a，b∈R，有（-b）*a=

-ab

若环R满足交换律则称为什么？

交换环

在Zm剩余环类中没有哪一种元？

不可逆元，非零因子

a与0的一个最大公因数是什么？

A

环R中满足a、b∈R，如果ab=ba=e（单位元）则称a是什么？

可逆元

在整数环中若c|a，c|b，则c称为a和b的什么？

公因数

最下的数域是什么？

有理数域

整数环的带余除法中满足a=qb+r时r应该满足什么条件？

0<=r<|b|

设F是一个有单位元（不为0）的交换环，如果F的每个非零元都是可逆元，那么称F是一个什么？

域

gcd（56，24）=？

8

整环具有的性质不包括

有零因子

不能被5整除的数是

323

在Z中，若a|bc，且（a，b）=1则可以得到什么结论？

a|b

如果d是被除数和除数的一个最大公因数也是哪两个数的一个最大公因数？

除数和余数

素数的特性之间的相互关系是什么样的？

等价关系

p与任意数a有（p，a）=1或p|a的关系，则p是？

素数

Z10的可逆元是？

7

任一数域的特征为？

p是素数，Zp域的特征为？

p

在R中，n为正整数，当n为多少时n1可以为零元？

无论n为多少都不为零元

特征为2的域是

Z2

3的201次方mod11？

3

在域F中，e是单位元，存在n，n为正整数使得ne=0成立的正整数n是什么？ 素数

设p是素数，则（p-1）!=?

-1

关于军队人数统计，丘老师列出的方程叫什么？

一次同余方程组

n被3，4，7除的余数分别是1，3，5且小于200，则n=？

187

6813模13和哪个数同余？

68

φ（10）=？

4

最早给出一次同余方程组抽象算法的是谁？

秦九识

Φ（9）=？

6

Φ（8）=？

4数学思维方式的五个重要环节：观察-抽象-探索-猜测-论证。

是

在今天，牛顿和莱布尼兹被誉为发明微积分的两个独立作者。

是

代数中五次方城及五次以上方程的解是可以用求根公式求得的。

否

任何集合都是它本身的子集。

是

空集是任何集合的子集。

是

“很小的数”可以构成一个集合。

否

A∩Φ=A。

否

如果两个等价类不相等那么它们的交集就是空集。

是

设R和S是集合A上的等价关系，则R∪S一定是等价关系。

否

三角形的相似关系是等价关系

是

a和b同余的充要条件是a，b除m后有相同的余数

是

设R和S是集合A上的等价关系，则R∪S一定是等价关系

如果一个非空际R满足了四条加法运算，而且满足两条乘法运算可以称它为一个环 是

设R是非空集合，R和R的笛卡儿积到R的一个映射就是运算

是{s与m的故事}.

中国的剩余定理又称孙子定理

是

整环一定是域

否

矩阵乘法不满足交换律也不满足结合律

否

整数的加法就是奇数集的运算

否

整环是无零因子环

是

域必定是整环

是

右零因子一定是左零因子

否

若n是奇数，则8|（n^2-1）

是

a是a与0的一个最大公因数

是

对于整数环，任意两个非0整数a，b一定具有最大公因数

是

在整数环中若（a，b）=1，则称a，b互素

是

用带余除法对被除数进行替换时候可以无限进行下去

否

计算两个数的最大公因子的最有效的方法是带余除法

否

Zm的每个元素都是可逆元或者零因子。

是

在Z中，若a|c，b|c，且（a，b）=1，则可以a|bc

否

Z81中，9是可逆元

否

设域F的单位元e，对任意的n∈N有ne不等于0

是

在Zm中等价类a与m不互素时等价环a是零因子

是

9877是素数

否

设域F的特征为素数p，对任意的a，b∈F，有(a+b)^p=a^p+b^p

Z91中，34是可逆元

是

费马小定理中规定的a是任意整数，包括正整数和负整数

否

欧拉在1743年，高斯在1801年也分别给出了同余方程组的解法 是

Zm中可逆元个数记为φ（m），把φ（m）称为欧拉函数

是

求取可逆元个数的函数φ（m）是高斯函数

否

设p是素数，则对于任意的整数a，有a^p=a(modp)

是

一次同余方程组在Z中是没有解的

否

在Zm中，a是可逆元的充要条件是a与m互素

是

某数如果加上5就能被6整除，减去5就能被7整除，这个数最小是20 否

s与m的故事篇五

英语小故事

The Fox and the Tiger

T---Tiger F---Fox R---Rabbit B---Bird

Fr---Frog

B----Bear

Tiger: I‟m a great tiger. I‟m very strong. I‟m very brave. I‟m the king of the forest.But now I‟m very hungry. I must find sth. to eat at once, or I‟ll die immediately. Oh, there‟s nothing here. And here is nothing, either. Oh, I want to have a rest. (Sleep soundly)

Fox: I‟m a fox. You can see, I‟m pretty and lovely. I‟m good at cheating 0and telling lies. Just now I cheated a crew out of a piece of meat. Mm, Mm, Mm. How delicious it is!

Tiger: Ah, a fox. A good meal. Ah, a good meal.

Fox: Oh, my God! What should I do? Yes, I have a good idea. Yes, a good idea. Hello! Tiger sister! How are you?

Tiger: Not so good. I‟m very hungry now. I want to eat you.

Fox: Oh, my dear! How dare you say that! I‟m the king of the forest! I‟m the king of the forest! If you want to eat me, I will let you die right now.

Tiger: She is the king. She is cheating me. I can‟t belive her. I‟m the king of the forest here. Fox: If you don‟t believe me, just follow me and see who is the king of the forest.

Tiger: Ok. Let‟s go.

Rabbit: I‟m a rabbit. I like to eat a turnip. Ah, a big turnip. Oh! It‟s too hard. I can‟t pull it out. Bird: I‟m a bird. Rabbit: Hi! Bird: Hi! What are doing here, Miss Rabbit? Can I help you?

Rabbit: Yes, please.

Frog: I‟m a frog. Hello! What are you doing here? What can I do for you?

R&B: Yes, come on!

Frog : Ok! I‟m coming!

Bear: I‟m a big brown bear. Hello, everyone! What are you doing here?

R,B&F: Come on! Come on! Mr. Bear! You are so strong. Please come here. There is a big turnip. We are all puling it out. Please come and help us.

Bear: Ok! I‟m coming.

Fox: Hello, Bear!

Bear: Hi, Fox. Oh, a tiger! (run away)

Fox: Hello, Frog!

Frog: Hi, Fox. Oh, a tiger! (run away)

Fox: Hello, Bird!

Bird: Hi, Fox. Oh, a tiger! (run away)

Fox: Hello, Rabbit!

Rabbit: Hi, Fox. Oh, a tiger! (run away)

Fox: Tiger, Now, you see. They are so frightened! They all run away!

Tiger: Yes, you are right. It‟s true. I‟m very sorry. You are the king of the forest. That‟s all right. I will run away. He is the king. He is the king.

Fox: Wa! There is a big turnip. Now, the turnip belongs to me.

小学英语寓言故事:Donkeys and his shadow

一个旅客雇了一头驴,骑着它到远处去。

A tourist hired a donkey, to Jizhaota to distant.

那天天气很热,赤日炎炎。 That weather is very hot, Chiri hothead.

他停下来休息,躲避在驴子的影子下,求个荫凉,避免暴晒。

He stopped to rest, refuge in the shadow of the donkey, and a shade to avoid exposure.

驴子的影子仅够遮蔽一个人,于是旅客和驴子的主人为了遮荫激烈地争起来,谁都认为自己才有这个权利。

Donkeys barely enough to cover the shadow of a person, then the owner of passengers and donkeys to shade fierce fighting, no one think they have this right.

驴子的主人坚持说他仅出租驴子本身,不出租驴子的影子。

Donkey owner insisted that he only letting donkeys themselves, not the shadow of letting donkeys. 那旅客说他雇的驴子包括驴子本身和影子。

The visitors said that he employed the donkeys themselves, including donkeys and shadow.

他们争论不休,以至互相打了起来。

They debate, and even fight each other up.

当他们打架时,驴子逃跑了。

When they fight, donkeys away.

这是说,人们往往为小事争吵不休,从而失去了最重要的东西。

It is said that people often trivial bickering, thus losing the most important things.

小学生英语寓言故事:The Lion and the Mouse

A LION was awakened from sleep by a Mouse running over his face. Rising up angrily, he caught him and was about to kill him, when the Mouse piteously entreated, saying: "If you would only spare my life, I would be sure to repay your kindness." The Lion laughed and let him go. It happened shortly after this that the Lion was caught by some hunters, who bound him by strong ropes to the ground. The Mouse, recognizing his roar, came and gnawed the rope with his teeth and set him free, exclaiming:

"You ridiculed the idea of my ever being able to help you, expecting to receive from me any repayment of your favor; now you know that it is possible for even a Mouse to con benefits on a Lion."

狮子睡着了,有只老鼠跳到了他身上。狮子猛然站起来,把他抓住,准备吃掉。老鼠请 求饶命,并说如果保住性命,必将报恩,狮子轻蔑地笑了笑,便把他放走了。不久,狮子真 的被老鼠救了性命。原来狮子被一个猎人抓获,并用绳索把他捆在一棵树上。老鼠听到了他 的哀嚎,走过去咬断绳索,放走了狮子,并说:

“你当时嘲笑我,不相信能得到我的报答, 现在可清楚了,老鼠也能报恩。” 这故事说明,时运交替变更,强者也会有需要弱者的时候。

英语短篇幽默故事

Matt and his wife lived in the country. Matt was very stingy and hated spending money. One day a fair came to the nearby town.

“Let‟s go to the fair, Matt,” his wife said, “We haven‟t been anywhere for a long time.”

Matt thought about this for a while. He knew he would have to spend money at the fair. At last he said, “All right, but I‟m not going to spend much money. We‟ll look at things, but we won‟t buy anything.”

they went to the fair and looked at all the things to buy. There were many things Matt‟s wife wanted to buy ,but he would not let her spend any money.

then , in a nearby field, they saw a small airplane.

“Fun flight!” the notice said, “$10 for 10 minutes.”

Matt had never been in an airplane and he wanted to go on a fun flight. However, he didn‟t want to have to pay for his wife, as well.

“I‟ve only got $10,” he told the pilot. “Can my wife come with me for free?” The pilot wasn‟t selling many tickets, so he said , “I‟ll make a bargain with you. If your wife doesn‟t scream or shout, she can have a free flight.”

Matt aGREed, and got into the small airplane with his wife.

the pilot took off and made his airplane do all kinds of things. At one moment it was flying upside down.

When the plane landed , the pilot said, “O.K. your wife didn‟t make a sound . She can have her ride free.”

“Thank you,” Matt said. “it wasn‟t easy for her, you know , especially when she fell out.”

英语幽默小故事

I'm Trying to Stop It "Boy, why have you got cotton-wool in your ear? Is it infected?" "No, sir, but you said yesterday that everything you told me went in one ear and out the other , so I am trying to stop it." “孩子，你为什么用棉花塞住耳朵？它感染了吗？” “没有，老师。可是你昨天说你告诉我的知识都是一个耳朵里进，一个耳朵里出，所以我要把它堵在里面。”

“I'm sorry ，Madam ，but I shall have to charge you twenty dollars for pulling your boy's tooth .” “Twenty d ollars! Why ，I understand you to say that you charged only four dollars for such work!” “Yes ，but this youngster yelled so terribly that he scared four other patients out of the office .” “对不起，夫人，为您孩子拔牙我要收取20美元。” “20美元！为什么？不是说好只要4美元。” “是的，但是你的孩子大喊大叫，把另外四个病人吓跑了。”

TWO： Teacher：We all know that beat causes an object to expand an cold cauese it to contract. Now，can anyone give me a good example? John：Well ，in the summer the days are long，and in the winter the days are short. 老师：我们都知道热胀冷缩的道理。现在，谁给我举个例子？ 约翰：嗯，在夏天天都长，在冬天天都短。

The lecturer on evolution had been going on for nearly two hours. then he started again, and said he:"Let me ask the evolutionist a question --- if we had tails like a baboon, where are they?" "I'll venture an answer, " said an old lady. "We have worn them off sitting here so long.". 教进化论的老师已经滔滔不绝地讲了快两个小时，他的话题又来了：“让我向进化论者提个问题——如果我们曾经像狒狒那样长着尾巴，那么现在尾巴到哪里去了？” “我来试试看，”一位老太太说。 “该是我们在这里坐这么久把它们磨掉了吧。”

英语幽默小故事中英文对照

Plagiarism{s与m的故事}.

A friend of mine who teachs European history at Washington University in St. Louis tell about the time he spotted a plagiarized term paper. He summoned the student to his office. "This isn't your work." he said. "Someone typed it for you straight out of the encyclopedia.

"You cann't prove that!" the student sputtered.

My friend amiled and show him the paper. Circled in red was: "Also see article on communism." 抄 袭

我有个朋友在圣路易斯的华盛顿大学教欧洲历史，他说有一次他发现了一篇抄袭的学期论文。他把那个学生叫到了办公室。“这不是你写的，”他说，“有人帮你从百科全书上原封不动地打印了下来。” “你没有证据。”那学生气急败坏地说。

我朋友笑了，他把论文拿给他看。用红笔圈出来的是：“也可参阅共产主义一文。”

Virtue

Many years after receiving my graduate degree, I returned to the State University of New York at Binghamton as a faculty member. One day in a crowded elevator, someone remarked on its inefficiency. I said the elevators had not changed in the 20 years since I began there as a student.

When the door finally opened, I felt a compassionate pat on my back, and turned to see an elderly nun smiling at me. "You'll get that degree, dear," she whispered. "Perseverance is a virtue."

美 德

获取研究生学位多年以后，我回到位于宾翰顿的纽约州立大学当教员。一天，电梯里很拥挤，有人抱怨电梯效率太低。我说自我在那里当学生起，20年来电梯一直没有换过。

最后当电梯门打开时，我感到有人在我的背上同情地拍了一下，回过头来我看到一位年长的修女正在朝我微笑。“你会拿到学位的，亲爱的，”她低声说道：“坚持不懈是一种美德。”

Difference

"I can always tell a graduate class from an undergraduate class," observed the instructor in one of my graduate engineering courses at California State University in Los Angeles. "When I say, 'Good afternoon,' the undergraduates respond, 'Good afternoon." But the graduate students just write it down."

区 别

“研究生班和本科生很容易就能区别开来，”在洛杉矶加利福利亚州立大学给我们研究生上工程学课的老师如此说。“我说„下午好‟，本科生们回答说„下午好‟。研究生们则把我说的话记在笔记本上。” Big Head

“All the kids make fun of me”the boy cried to his mother.“They say I have a big head”

“Don't listen to them.”his mother comforted him.“You have a beautiful head .Now stop crying and go to the store for ten pounds of potatoes”

“Where's the shopping bag?”

“I haven't got one,use your hat.”

大脑袋

“所有的孩子都拿我开玩笑，”小男孩哭着跟妈妈说：“他们说我长了一个大脑袋。”

“别听他们的，”他妈妈安慰说：“你的脑袋长得很漂亮。好了，别哭了，去商店买10磅土豆来。” “购物袋在哪？”

“我没有购物袋，就用你的帽子吧。”

Good Boy

Little Robert asked his mother for two cents. "What did you do with the money I gave you yesterday?" "I gave it to a poor old woman," he answered.

"You're a good boy," said the mother proudly. "Here are two cents more. But why are you so interested in the old woman?"

"She is the one who sells the candy."

好孩子

小罗伯特向妈妈要两分钱。

“昨天给你的钱干什么了？”

“我给了一个可怜的老太婆，”他回答说。 “你真是个好孩子，”妈妈骄傲地说。“再给你两分钱。可你为什么对那位老太太那么感兴趣呢？”

“她是个卖糖果的。”

Where is the father?

Two brothers were looking at some beautiful paintings.

"Look," said the elder brother. "How nice these paintings are!"

"Yes," said the younger, "but in all these paintings there is only the mother and the children. Where is the father?"

The elder brother thought for a moment and then explained, "Obviously he was painting the pictures." 父亲在哪儿？

兄弟俩在看一些漂亮的油画。

“看，”哥哥说，“这些画多漂亮呀！”

“是啊，”弟弟说道，“可是在所有这些画中，只有妈妈和孩子。那爸爸去哪儿了呢？”

哥哥想了会儿，然后解释道：“很明显，他当时正在画这些画呗。”

The wolf and the sheep

A wolf had been badly wounded by dogs. He lay sick and maimed in his lair.

He felt very hungry and thirsty. When a sheep passed by, he asked him to fetch some water from the stream.

"If you bring me the water," he said, "I will find means to get some food."

"Yes," said the sheep, "if I bring you the water, you would undoubtedly make me your food." 一只狼被狗所咬，伤势很严重，痛苦地躺在巢穴里，不能外出觅食。他感到又饿又渴，这时，他看见一只羊，便请求他到附近的小河里为他取一点水来。“你给我一点水解渴”，他说，“我就能自己去寻找食物了。”“是呀”，羊回答说，“如果我给你送水喝，那么我就会成为你的食物。”

英语小故事短文:狐狸和乌鸦

The Fox and the Crow

A Fox once saw a Crow fly off with a piece of cheese in its beak and settle on a branch of a tree. „That‟s for me, as I am a Fox,‟ said Master Reynard, and he walked up to the foot of the tree. „Good-day, Mistress Crow,‟ he cried. „How well you are looking to-day: how glossy your feathers; how bright your eye. I feel sure your voice must surpass that of other birds, just as your figure does; let me hear but one song from you that I may greet you as the Queen of Birds.‟ The Crow lifted up her head and began to caw her best, but the moment she opened her mouth the piece of cheese fell to the ground, only to be snapped up by Master Fox. „That will do,‟ said he. „That was all I wanted. In exchange for your cheese I will give you a piece of advice for the future .‟Do not trust flatterers.‟

英语故事短文:小马过河

How a Colt Crossed the River

One day, a colt took a bag of wheat to the mill. As he was running with the bag on his back, he came to a small river. The colt could not decide whether he could cross it. Looking around, he saw a cow grazing nearby. He asked, “Aunt Cow, could you tell me if I can cross the river?” The cow told him that he could and that the river was not very deep, just knee high.

The colt was crossing the river when a squirrel jumped down fron a tree and stopped him. The squirrel shouted, “Colt, stop! You‟ll drown! One of my friends drowned just yesterday in the river.” Not knowing what to do, the colt went home to consult his mum.

He told his mum his experience on the way. His mother said, “My child, don‟t always listen to others. You‟d better go and try yourself. Then you‟ll know what to do.” Later, at the river,the squirrel stopped the colt again. “Little horse, it‟s too dangerous!” “No, I want to try myself,” answered the colt. Then

he

s与m的故事篇六

数学故事

c十年高考动词时态和语态考题汇编

1. —Can I help you, sir? —Yes, I bought this radio here yesterday, but it ______.

A. didn’t work B. won’t work C. can’t work D. doesn’t work(NMET 1996)

2. —_____my glasses? —Yes, I saw them on your bed a minute ago. (NMET 1996)

A. Do you see B. Had you seen C. Would you see D. Have you seen

3. Helen ___her key in the office so she had to wait until her husband ___home.(NMET 1996)

A. had left; comes B. had left; would come

C. had left; came D. left; had come

4. —Who is Jerry Cooper?

—______? I saw you shaking hands with him at the meeting. (NMET 1997)

A. Don’t you meet him yet B. Hadn’t you met him yet

C. Didn’t you meet him yet D. Haven’t you met him yet

5. I first met Lisa three years ago. She ___at a radio shop at that time. (NMET 1997)

A. has worked B. was working C. had been working D. had worked

6. —Alice, why didn’t you come yesterday? — I _____, but I had an unexpected visitor.

A. had B. would C. was going to D. did (NMET 1997)

7. —Nancy is not coming tonight. —But she _____！ (NMET 1998)

A. promise B. promised C. will promise D. had promised

8. —You haven’t been to Beijing, have you? —_____. How I wish to go there! (NMET 1998)

A. Yes, I have B. Yes, I haven’t C. No, I have D. No, I haven’t

9. —Hi, Tracy, you look tired. —I am tired. I _____the living room all day.(NMET 1998)

A. painted B. had painted C. have been painting D. have painted

10. Shirley ____a book about China last year, but I don’t know whether she has finished it yet. (NMET 1998)

A. has written B. had written C. wrote D. was writing

11. The price _____, but I doubt whither it will remain so. (NMET 1999)

A. went down B. will go down C. has gone down D. was going down

12. —Hey, look where you are going! —Oh, I’m terribly sorry. ______. (NMET 1999)

A. I’m not noticing B. I wasn’t noticing

C. I haven’t noticed D. I don’t notice

13. —You have left the light on. —Oh, so I have. ____and turn it off. (NMET 2000)

A. I’ll go B. I’ve gone C. I’m going D. I’m going to go

14. —How are you today? —Oh, I ___as ill as I do now for a very long time.(NMET 2000)

A. didn’t feel B. wasn’t feel C. don’t feel D. haven’t felt

15. The eyewitness said that the day ____ when he saw the UFO passing across the sky.

A. is breaking B. was breaking C. broke D. was to break(NMET 2000)

16. Old McDonald gave up smoking for a while, but soon____ to his old ways. (2000spring）

A. returned B returns C. was returning D. had returned

17. —You're drinking too much. —Only at home. No one_____ me but you. (2000spring)

A. is seeing B had seen C. sees D. saw

18. Selecting a mobile phone for personal use is no easy task because technology ____so rapidly. (NMET 2001)

A. is changing B. has changed C. will have changed D. will change

19. I ___pong-pong quite well but I haven’t had time to play since the New Year.

A. will play B. have played C. played D. play (NMET 2001)

20. Visitors _____not to touch the exhibits. (NMET 2001)

A. will request B. request C. are requesting D. are requested

21. Hundreds of jobs______if the factory closes. (2001spring)

A. lose B. will be lost C. are lost D. will lose

22. I've won a holiday for two to Florida. I______ my mum. (2001spring)

A. am taking B. have taken C. take D. will have taken

23. A new cinema_____ here. They hope to finish it next month. (2001spring)

A. will be built B. is built C. has been built D. is being built

24. I wonder why Jenny _____us recently. We should have heard from her by now (NMET 2002)

A. hasn’t written B. doesn’t write C. won’t write D. hadn’t written

25. —You haven’t said a word about my new coat Brenda. Do you like it? —I’m sorry

I ____anything about it sooner. I certainly think it’s pretty on you.

A. was saying B. don’t say C. won’t say D. didn’t say (NMET2002)

26. John and I friends for eight years. We first got to know each other at a Christmas party. But we each other a couple of times before that. (2002spring)

A. had been; have see