地震逃生知识英文作文（最新20篇）

The summer vacation had come round again. I was happy that I could forget

about school at least for a while. Lest I fool around all through this summer

vacation, I made a plan as to how to spend it. First, I thought I should go over

all those things my teachers taught in the previous term so that I could have a

better understanding of them. Then I thought I should take up some forms of

exercise, such as walking, running and rowing, to keep me physically strong. It

stood to reason that with such a good plan I should make the best of my vacation

time. I did, because I lived up to what I had planned.

在生活中，我们可以发现许多神奇的景象，今天，我做了一个小实验，让我又学到了不少新知识。

星期天，我在家中闲着无事，便拿出几个鸡蛋来“研究”。有个鸡蛋一不小心掉进了桌子上的水盆里，一会儿就沉了下去，我突发奇想，如果在水里加入一些东西，鸡蛋是不是就浮起来了？说干就干，可在这时，我又愣住了，加什么东西会浮起来呢？这时，我的目光落在了盐上，死海的盐很多，人可以浮在海面上，那鸡蛋应该也可以浮起来。我往水里放了四五勺盐，然后将鸡蛋放进去，可还是没有浮上来，我一生气，将整袋盐都倒了进去，鸡蛋终于浮上来了，我惊喜万分。可却不知这是为什么，便去请教“无声的老师”。

原来，鸡蛋之所以在水中下沉，是因为鸡蛋的密度大于水的密度。而当往水里添加食盐后，食盐在水中溶解，水的密度渐渐增大，浮力也渐渐增大，当继续添加食盐，使水的密度足够大时，鸡蛋便浮起来了。

看吧，生活中的知识无处不在，只要细心观察、不断探索，就一定能发现更多的奥秘！

地震过后，经过强烈的晃动和山上碎石的狂轰乱炸后，小学旁唯一的一座木吊桥已经面目全非，十几个死里逃生的孩子眼看着桥面上最后一块木板也慢慢滑进了翻滚着黄泥的怒涛中……

孩子们灰头土脸，呜呜地哭泣着，紧紧抱成一团。他们已经被瞬间的地动天摇夺去了魂魄。现在，连回家的路也被切断了。

大灾无情，人间有爱。三十三位从天而降的解放军战士越过碎石，穿过尘埃，奇迹般地出现在他们面前。队长凝望着那三条湿漉漉、光秃秃、冷冰冰的铁索，又低头看看铁索下那张着血盆大口的大河，思索着让孩子们回家的办法。

那十七名小学生稚嫩的双眼仍噙满了恐惧，他们不知所措，担心震后仍未找到的同学，担心山那头的家人，甚至担心余震后的碎石会把他们再次带入无尽的黑暗……

解放军叔叔疲惫的眼神此时却迸发出异常的坚毅。队长猛地回过头，对战友们说：“趴下，搭人桥”！一个个结实的肩膀紧靠着第一根冰冷的铁链，铁板般的腹肌和第二根铁链拧在了一起，磨破的军鞋死死勾住湿滑的第三根铁链。

瞬间，一切就绪，这是一座用生命搭起的桥梁。

汗水从他们的脸上滴了下来，眨眼就被下面的洪魔吞没了，他们都知道掉下去会是怎么样的结果，但为了这些稚嫩的生命，他们愿意将自己的身躯架在与死神交界的地方。

他们的手指像鹰爪般死死扣在铁链的缝隙中，那无情的铁链像一只只恶狗，死死咬住了他们的手，为了控制铁链的摆动幅度，他们任凭指间的鲜血顺着铁链滑落，没有一个人松手。战士们咬紧牙关，忍受着背上的重压，却面带微笑，鼓励每一个爬到自己背上的孩子，他们微调自己的脊背，在冷酷无情的灾难面前，默契地完成着这场生命的接力赛。

当最后一名小学生顺利通过，他们终于可以喘口气，但是僵硬麻木的双腿，已经很难让战士们挪动身体，他们相互搀扶着、鼓励着回到岸上。此时，大家才发现自己双手早已冻青，血肉模糊了……

天灾无法避免，但如何抗灾事在人为。灾难后面总有一些可爱的身影感动着我们，他们的无私奉献激励了全国人民，完美地诠释了何谓“多难兴邦”，让我们更团结，让战胜灾难的决心更坚定！

It is indeed difficult to live without a mobile phone as it helps us in day

to day activities. I cannot live without a mobile phone. Todays generation uses

mobile phones for chatting, surfing and playing games. They dont use the mobile

phone for the real purpose. I admit that living wothout a mobile phone is

extremely difficult but I can live without addicting apps like Facebook, Twitter

etc. The iPhone is a gadget that is encouraging to use social apps and addicting

games. These gadgets though facilitate our work but are making us their slaves.

For example, if a persons iPhone is not working properly, he will be filled

with anger. As new technology is creating new gadgets, so are people raising new

demands. They also hamper academics. Buy a mobile phone but use it for something

productive.

Long, long ago, on a cross the ocean, there is a father with a 6 years old and his wife and son to the United States. One day, when the man in the cabin with a fruit knife cut apple to his son, the ship suddenly violent shaking, a knife in a man falls into his chest. Men stood up slowly, at the time of the son do not pay attention to with their thumb to wipe the blade on the blood.

Three days later, the man to take care of the son, as usual with him blowing sea breeze, watching the blue sea. Like business as usual, but the son not to notice the father every minute than a minute on the weak, his eyes see the sea is so sad.

Reached on the eve of next to the man came to the son, the son said: "tomorrow to see your mother, tell her that I love her." Say that finish, the son left a deep kiss on his forehead.

The ship to the United States, I recognized my mother, son in the crowd shouted: "mom! Mom!" Just then, a man has to fall on his back, chest blood like a blowout.

Autopsy results for all shocked: the knife very accurately ed in his heart, but he live for three days, and not be found. The only possible explanation is because the wound is too small, yes, it is forced to cut off the attached together in the same heart, lasted for three days supply of blood.

This was a rare miracle in medicine. If you gave a name to this miracle that is called the father of it.

1、Practice makes perfect.

熟能生巧。

2、God helps those who help themselves.

天助自助者。

3、Easier said than done.

说起来容易做起来难。

4、Where there is a will,there is a way.

有志者事竟成。

5、One false step will make a great difference.

失之毫厘，谬之千里。

6、Slow and steady wins the race.

稳扎稳打无往而不胜。

7、A fall into the pit,a gain in your wit.

吃一堑，长一智。

8、Experience is the mother of wisdom.

实践出真知。

9、All work and no play makes jack a dull boy.

只工作不玩耍，聪明孩子也变傻。

10、Beauty without virtue is a rose without fragrance.

无德之美犹如没有香味的玫瑰，徒有其表。

11、More hasty,less speed.

欲速则不达。

12、Its never too old to learn.

活到老，学到老。

13、All that glitters is not gold.

闪光的未必都是金子。

14、A journey of a thousand miles begins with a single step.

千里之行始于足下。

15、Look before you leap.

三思而后行。

16、Rome was not built in a day.

伟业非一日之功。

17、Great minds think alike.

英雄所见略同。

18、well begun,half done.

好的开始等于成功的一半。

19、It is hard to please all.

众口难调。

20、Out of sight,out of mind.

眼不见，心不念。

21、Facts speak plainer than words.

事实胜于雄辩。

22、Call back white and white back.

颠倒黑白。

23、First things first.

凡事有轻重缓急。

24、Ill news travels fast.

坏事传千里。

25、A friend in need is a friend indeed.

患难见真情。

26、live not to eat,but eat to live.

活着不是为了吃饭，吃饭为了活着。

27、Action speaks louder than words.

行动胜过语言。

28、East or west,home is the best.

金窝银窝不如自家草窝。

29、Its not the gay coat that makes the gentleman.

君子在德不在衣。

30、Beauty will buy no beef

.漂亮不能当饭吃。

31、Like and like make good friends.

趣味相投。

32、The older,the wiser.

姜是老的辣。

33、Do as Romans do in Rome.

入乡随俗。

34、An idle youth,a needy age.

少壮不努力，老大徒伤悲。

35、As the tree,so the fruit.

种瓜得瓜，种豆得豆。

36、To live is to learn,to learnistobetterlive.

活着为了学习，学习为了更好的活着。

[常见英文谚语励志篇

The cartoon given above tells us that there are two persons who are arguing with each other about the importance of book Knowledge and experience. In fact, knowledge can be acquired from many sources. These include reading books, classroom activities and practice.

The knowledge we gain from books and formal education enables us to learn about things that we have no opportunity to experience in our daily life. First of all, we can study all the places in the world and learn from people we will never meet in our lifetime, just by reading about them in books. Second, we can also develop our analytical skills and learn how to view and interpret the world around us in different ways. Last but not least, we can shuttle between the past and the future by reading books. In this way, we wont repeat the mistakes of others.

Practice, on the other hand, offers us more useful knowledge. In fact, as we all know failure is the mother of success. Moreover, if one wants to make new advances, it is necessary to act. Finally, one can apply the skills and insights gained through the study of books to practical experience, making an already meaningful experience more meaningful.

dear mr.xxx,

im sorrto tell you that i caught a cold and im not feeling well now.i am adviced to stain bed for two dayand cant go to school then.but i think ill get well soon and be back the daafter tomorrow.

yoursincerely,

xxx

青海玉树地震作文字一方有难，八方支援。青海玉树指挥部发布急需物资说明：目前，灾区急需挖掘设备、帐篷、被褥、生活物资、防寒物资。有意者可与玉树州政府副秘书长黄立明联系。家评

玉树——离天那么近的地方，那里的人民一定有玉石的坚强，有大树的挺拔，深深地为你们祈祷。

一条黑色的消息出现在眼前，脑海里不由得冒出那残墙断垣的痛苦画面，内心如同灌了铅一般沉重。希望外界援助能尽快到达灾区，愿逝者安息，愿地震灾区的人们勇敢渡过难关！

玉树地震经过，又来了，早上听闻此消息时，心情为之一沉，希望玉树人扛住，我们在深圳为你们祈福，天佑玉树！

地震无情，人有情，愿此次地震伤亡最少；愿那些倒塌的房屋能尽早重建，愿村民们尽早恢复往日的生机，走出地震阴影，愿所有的伤害降到最低；愿地震永远不要再来了。

早上还在睡梦中的时候，朋友来电，青海地震了！猛一惊醒，想起汶川受难的那些同胞们，不知道此刻灾情如何，但从心底为他们祈祷，愿他们一切安好！

今天同事们的心情很沉重，都通过各种途径关注玉树大地震的情况，我不能去参加救援，只能默默地为玉树人民加油鼓劲，好想听到灾区人民平安无恙的消息，合上双手，为玉树人民祈福！

看到新闻上说玉树那里死伤人，想起了汶川可怕的场面，触目惊心，又会有多少人无家可归，又会有多少人顿时和亲人阴阳两隔，我的心被揪起来，如同在实习时看到那些含泪为汶川捐款的全国同胞们。玉树，一定要坚强起来。

知道那时你是因为听了我随口的一句话去到了青海，今天听说那边地震了，我很担心你，希望你平安。

希望更多的人被救出来，希望更多的人加入到救援队伍！要珍惜每一天的生命！每一天都要活得有价值！

地震，是自然对人类的考验，事实证明，我们是胜者。因为生命还在继续，生活充满希望，灾区的同胞们，别怕，房屋倒了，我们会伸出有力的臂膀；别怕，梦想破了，我们会送去新的希望；孩子，你们一定要学会坚强，地震只能震垮房屋，却震不垮爱心和希望，孩子，别哭！我们定会不离不弃，心心相依，所有祈福，可以为那些挺过灾难的生者带来希望！也可以为那些赶赴一线救人的勇士们加一把油！

让我们携手度过灾

难，昂起头，你们会在废墟中看到希望和明天！玉树临风本是一个美好的名字却与灾难相连愿玉树人民早日重建家园远离灾难。

地震有前兆吗人间有大爱，我们与玉树心心相连！关注青海，抗震救灾，我们在一起！

在玉树，在仙境一般的地方，还有好多朋友生活在那里，不知情况怎么样了，希望一切安好！保佑他们吧！

不论发生什么，我们都要坚强勇敢地活着，为爱自己的人，也为自己爱的人！为深陷灾难的人们祈福，珍惜自己拥有的，不抱怨！感恩生活。

让我们一起为青海地震祈祷：“灾难已到达顶点，何处是你救助之标帜？万千世界的救助者啊！

时间过得如飞一样快，新的一年又来到了，而我今年却过了一个不一样的新年。而是在深圳过的，在这新的一年里我学到了很多知识。

一天中午，我们在吃午饭时，大妈说：“我们下午去看电影吧。”我和弟弟既开心又激动，说：“好啊，好啊！”大妈又说：“好，那我就买三张票。”

我们吃完了，我去床上睡一会儿觉。没过一会儿，大妈过来叫我起床。我心想：我不想离开暖和的被子，算了还是起来。大妈说：“走吧，去看电影。”我们换好鞋，乘着电梯到了楼下。大妈把电动车骑过来，我们坐着车到了电影院门口。不过，看一下时间，我们到楼上影院。我们取好了电影票，就进入了放映大厅。时间刚刚好，电影刚刚开始放。

突然一名警察说了一些知识，比如：遇到了坏人怎么办，如果有人来敲门……我听了这些知识后，屏幕上播放了一段这样的视频，我们看了这些视频，才恍然大悟，知道了以后如何保护自己。

电影结束了，我们排着队走出了电影院。我走在回家的路上，就在想这些知识要把这些知识背下来，以后好知道遇到坏人该怎么办。

《鲁滨逊漂流记》是一本很好看的书。

这本书讲了鲁滨逊因航海遇上风暴，又被海盗抓住，当了俘虏，逃出生天后，他又面临一个更大的敌人——大自然。他救出一个即将被吃的黑人，取名星期五，和他一起逃离荒岛。

鲁滨逊能逃出荒岛，靠的是知识与劳动。没有知识，他将不知如何获得食物以及一切生存品。没有劳动，他无法得到房子甚至所以生存品。他就是具备了知识与劳动，所以打造一片天地，只有具备了知识与劳动，才能逃出荒岛。不管遇到再大的麻烦，都会被一一破解。他知道在荒岛上该如何生存，如何逃离荒岛，他让我佩服。

再看看我自己，实在我自己，实在很惭愧。我虽然看了许多求生节目。但如果我真实的遇难时，我无法自己求生。有一次，我正在看荒野求生，爸爸问我在沙漠上应该怎么办，我说应该先搭庇护所，爸爸让我到后山去搭一个，我信心十足的走向后山，弄了十分钟，我赶紧跑了回来，打开空调，爸爸急忙把空调关了。爸爸说：“在热的一种环境里一下子到了冷的环境里，对身体不会。你的知识与劳动都没有具备，根本不能生存。”

爸爸说的对，我没有鲁滨逊那么厉害，我会继续努力的。

手臂有点不适，就不出去玩，看了电影《辛亥革命》，那滚滚的硝烟，那慷慨激昂的话语，时刻萦绕我心。

难忘剧中孙中山现身说的“前线赴死易，唤醒生者难”，语气中透露出一种无奈！流血牺牲又有何妨，又有何惧，但怕只怕这些也只是徒劳无功而已。

在战场上，血流成了江海，硝烟弥漫成霾，说实话在战场上实在不容易，有无数穿越在枪林弹雨中，他们无怨，亦无悔，在战场上的战士们，他们只有一个心愿，用自己的生来换来人民的清醒，换来国家的富强！就像宋庆龄说的那样，中国是一只沉睡的狮子，可他已经沉睡太久了，现在是该醒过来了，是该重头收拾旧山河！那种被轻易给放的异族，任人宰割的时代终于要结束了！

战争开始了，无数人倒在硝烟之中，他们倒下的那一刻钟，又有人后面前赴后继，在浓浓的硝烟中，又失去父母的……他们勇敢前进，勇于挑战、除了责任，还有信仰！

辛亥革命是成功了，同时也失败了，无数革命烈士用生命换来的胜利的果实被北洋军阀统领哀世凯窃取了。新一轮战斗又开始了……。

我们这些新一代人如何绝地反击，让中国立于世界强国之前列呀！

a letter to my parents

dear mom & dad,

i love you! i love you so much! i love you with all my heart!

thank you so much for bringing up! thank you so much for raising me. i know

how hard you’ve worked during the past years. i can image how many difficulties

and obstacles you’ve conquered. i can imagine all the problems you have faced

and all the sweat and tears you have shed to make my life better. i can fully

understand what a huge responsibility it is to raise a child. you’ve been very

patient with me. you’ve encouraged me and you’ve helped me. you’ve tried your

hardest to give me the best things in life. you’ve made a lot of sacrifices and

many difficult choices. i also know that you have great expectations of me. you

want me to be very successful and happy. you want me to be the best person i can

be. you want me to do great things with my life. you want me to make the world a

better place. i know you have so many so many hopes and dreams for my

future.

today i want to tell you something extremely important.

today i want to tell you that you dont need to worry about me any more.

im grown up! i will be responsible for my life and for my future. i will study

very hard. i will exercise everyday to keep fit. i will read english every

morning and every night. i will make the best use of every spare minute. i will

be happy, confident, positive and energetic everyday!! i will develop good

habits and use them to constantly improve myself. i will never do anything that

would harm my body or my mind. i will never do anything that would make you feel

disappointed or ashamed. i will learn as much as i can and become smarter and

stronger every day. i have learned by watching you that the best way to reach my

goals is to work hard and never give up. you’re my best role models. you set a

great example for me.

i have so many great dreams. i know that realizing these dreams will take a

lot of time and effort. but dont worry about me. i have strong confidence in

myself. i know if i keep trying, keep working hard and keep dreaming, i will

definitely realize all my dreams. i will be somebody special. but i will not

only care about myself. i will contribute to my school, my hometown and my

country. i will contribute to society. i will use all my abilities and talents

to help my family and my country have a glorious future. i will make a

difference in this world.

dear mom and dad, you’ll be proud of me! you will see great results from

all your hard work and sacrifice. thank you very much for your continued

support! thank you very much for your patience, love and understanding. i love

you! i appreciate you! i’m very proud of you!

exercise every day to keep healthy! enjoy life every day and stay happy! my

only hope for you is you both to enjoy continued health and happiness. you

brought me into this word to share your life. i will do my best to make sure

each day of it is filled with joy and pride.

mom & dad, you are the best parents in the world! i don’t know what i

would have done without you.

all my everlasting love,

your daughter

Dear Mr. Li

Hello!

Time flies, time flies. Unconsciously, I have been in the national life

insurance for ten years. After ten years of insurance career, I suddenly

realized the value of life. With gratitude, I would like to eXpress my cordial

greetings and sincere thanks to you! Thank you for your support and help in the

past. Thank you for making me full of confidence and courage in the insurance

industry and enjoy the harvest and joy from it! As the saying goes: "receive

peoples gratitude, when the spring to repay!" What you have given me is a heavy

trust. I understand that only the insurance road has been going on, has been

walking well, is the biggest return to you! Please believe that enthusiasm and

enthusiasm of HongXia will always be by your side. Insurance, as a way of life

arrangement in the future, is being accepted and loved by more and more people.

I am honored to be your life insurance financial consultant and have the

opportunity to serve you! In the past days, because of insurance, we have more

contacts and eXchanges. Your open-minded and wise, understanding and trust, let

me be inspired and grateful. Since I entered the insurance industry, insurance

has made my heart become more broad and integrated, strong and enterprising.

When my heart is frustrated and hit, when I think of the support and trust of

many customers and the eXpectation of my family, I dare not let myself slack off

and continue to move forward bravely in this industry.

Calm and tranquility are the embodiment of life power, which comes from the

inner calm and security. Although life insurance cant resist risks, it can make

people feel sad and soothe the soul, and let the people who love us and those we

love deeply feel a continuous love and responsibility, so that the courage to

live and the vision of creating a new life cant be achieved by other goods and

services. Therefore, I have warned myself more than once that I should never

sell insurance to others because of my love and never say "no" to insurance

easily! I want to go on firmly in the insurance industry, and give more people

satisfaction insurance services! Its the beginning of the year again. Thank you

for giving me the opportunity to learn from you. I also sincerely wish you good

health, smooth work, harmonious family, prosperous business and prosperous

career! For myself, I will continue to learn and forge ahead to become more

substantial and professional, I will continue to provide you with the most

professional, the most perfect, the best quality service! I hope you can

continue to give me more support and help in the future, let me give security to

more people and more families!

China Life Dong HongXia to January 2013

今天下午阳光明媚，我们五年级全体学生在老师的带领下，整齐有序地走进多媒体教室，共同倾听了消防讲座。

首先，杨志栋叔叔先让我们看了美国消防电影—回火。接着，他又一一给我们介绍了消防栓、室内消防器、烟雾感应器、高压水枪、云梯等消防用具。让我们更多的了解了这些东西的作用，大大丰富了我们的知识面。

然后，他又简单的告诉我们，逃生时可用毛巾捂住口鼻，棉被包在身上。而在逃生过程中，应有老师看护和监督。听了这些方法，我们对急救措施又有了新的概念。后来，他向我们介绍了危险意识的危险源，有明火、烟、楼梯、拐角、急下坡、拥挤、踩踏等。让我们都深受启发。

今天的消防讲座，不仅让我们了解了消防知识，还让我们充实了自己的知识面。可真是收获不小、受益匪浅啊！

每年夏天，很多地方都会连续下雨，导致河水猛涨，引起洪水。洪水会把别人的家园冲走，甚至把别人的生命夺走。洪水好像一头野兽，真可怕！

为了增强村民的抗洪防洪意识，我们大岙村的领导组织了一场逃生演习。当洪水来临时，我们要有次序地走到临时避难处，躲避洪水对我们的袭击。

演习开始了。村领导说：“洪水来了，危险，快跟我们走！”我们跟着村领导来到很高的山上，那里有一座大房子，房子外面种了许多花草树木，真漂亮呀！原来这座大房子就是临时避难处。我们走进房子里面看了看，里面有厨房、餐桌、电视、吊灯、风扇等，东西真齐全啊！村领导给我们讲解了一些抗洪的知识，然后就带着我们下山了。

回来的路上，我心里很激动，因为今天我学到了很多抗洪防洪的知识。以后，当面临洪水时我们就不会再害怕了。

今年这个年，古今实罕见。

人人戴口罩，个个遮半脸。

新冠肺炎毒，源头在武汉。

九省通衢地，人流涌年关。

传染无踪影，风声鹤唳传。

北宸寄民生，快速启预案。

封城兼封路，全民作动员。

信息勤发布，居家保平安。

遥忆零三年，全国防“非典”，

组织加科技，天公也垂怜。

烈日几曝晒，瘟神化紫烟。

零八多事秋，地震发汶川。

山崩河晏塞，城池化泥丸。

红星映灾区，众手建家园。

春风几度拂，旧貌换新颜。

俄而洪波起，南北水连天。

众志筑长城，江河绝水患。

组织动员力，民族的中坚。

回顾抗战时，民国泥沙散。

蚕虫食桑叶，月余失蒙满。

南京大屠杀，血染江汉关。

重庆大轰炸，民生惨人寰。

放眼看世界，最雄美利坚。

称霸海内外，民生却多艰。

感冒寻常病，死亡竟数千。

澳洲亦先进，山火无人管。

烈熖逼悉尼，远超大兴安。

考拉葬火海，总督不拨钱。

首都放熖花，林海化焦炭。

回望大中国，时逢尧舜天。

国强傲欧美，长剑抗霸权。

扶贫摘穷帽，决胜史无前。

全民奔小康，人均万美元。

腾飞争朝夕，喜迎首百年。

瘟君生忌妒，施毒兴波澜。

怎奈金刚罩，防护保安全。

制度构天网，众志成城坚。

科技舞东风，烈火烧纸船。

闭门神思驰，潮涌扬征帆。

慎独养精锐，抖擞迎春天!

2008年汶川大地震，是我国唐山大地震伤以来亡最惨重的一次大地震，为纪念汶川大地震，减少人员伤亡，我们学校也举行了地震演习。

第二节课下课后，老师对我们说：“同学们上完厕所后，拿一本厚书顶在自己头顶上，准备地震演习。”

尖锐刺耳地警报铃声一响，同学们“嗖”的一下全钻到了桌子底下，几分钟后，老师让我们手拿着书顶在头顶上，跑到国下站队集合，接着老师又指挥我们头顶着书蹲下等待，最后，杨老师给我们讲了明天正式地震演习的规矩：第一步，警报铃声响后，我们应该头顶着书钻到桌子底下，第二步，老师会提醒我们什么时候跑出去，到国旗面前站成体育队形集合。地震演习的时候不能说说笑笑，要严肃认真对待！

我一定要学会发生像地震、火灾等这样的灾害时，时刻有所准备，学会自我保护，自救的方法，把灾难降到最低。

“嘟－嘟－”咦，这是什么声音？哈！原来是我们学校在举行地震演练。

我们本在教室里朗朗地读书，忽然，一声哨响打断了我们，大家便慌慌张张地躲到桌子底下，有的人竟然直接以箭一样的速度冲出教室，要不是老师把他们叫了回来，他们恐怕已经跑到操场上去了。哈哈，同学们也太滑稽了：比较胖的同学，一钻到桌子底下就出不来了；比较高的同学，钻到桌下把桌子都顶了起来。

过了一会儿，警报声响起，同学们像脱缰的野马一样冲出教室。在走廊排队时，我被大家撞倒了，由于现场十分混乱，有不少人从我的背上踩过、跨过，害得我洁白的衣服上又多了几个“印章”。我等啊等，等了3分钟，在我们班前面的五（1）班还是迟迟不肯向操场“进发”。我心想：这五（1）班，蜗牛的速度都是他的十倍，如果真的地震了，以这么慢的速度，我们岂不是要命丧黄泉了？……想着想着，队伍终于浩浩荡荡地出发了。

等我们到达操场，警报已经解除，我们心中的大石头终于落了地，又浩浩荡荡地向教室进发……

Dear Sir,

I saw your advertisement for "the perfect lighter" in Sunday Times last

week and immediately sent off a ￡2 postal order and the completed form for the

lighter.

Imagine my surprise when all I got in return was a box of matches! I could

understand a mistake. I might even pardon a joke. But in this case, your

advertisement is a deliberate lie since a friend of mine who also sent the

coupon got the same result.

I think its a shame to promise an economical lighter when in fact you are

not selling a lighter a1 all. Instead of saying it works quickly, you should

admit that you are offering matches. And what about "only" ￡2: I usually pay 10

pennies for a box of matches, and they are often given away free.

I regard your advertisement as a serious deception and demand that you send

me my money back immediately. Otherwise I will take active steps to make sure

the Consumers Association hear about it.

Yours faithfully,

Peter Li

牙齿是由哪几部分组成的，是怎样分类的？

从牙齿的外观上看，牙齿有牙冠、牙根及牙颈三部分组成。牙冠是牙体外层被牙釉质覆盖的部分，也是发挥咀嚼功能的主要部分，在正常情况下，牙冠的大部分显露于口腔，称为临床牙冠。牙根是牙体外层由牙骨质覆盖的部分，也是牙齿的支持部分；牙齿有的是单根牙，有的是多根牙，每一个牙根的尖端，称为根尖；每个根尖都有通过牙髓血管神经的小孔，称为根尖孔；正常情况下，牙根整个包埋于牙槽骨中。牙冠与牙根交界处呈一弧形曲线，称为牙颈，又名颈缘或颈线。

从牙齿的剖面看，牙体由牙釉质、牙骨质、牙本质和牙髓四层组成。牙釉质构成牙冠的表层，为半透明的白色硬组织，是牙体组织中高度钙化的最坚硬的组织。牙骨质是构成牙根表层的、色泽较黄的硬组织。牙本质构成牙体的主体，位于牙釉质与牙骨质的内层，不如牙釉质坚硬，在其内有一空腔称为牙髓腔。牙髓是充满在牙髓腔中的蜂窝组织，内含血管、神经和淋巴。是牙体组织中唯一的软组织。

根据牙齿的形态特点和功能特性将牙齿分为切牙、尖牙、双尖牙、磨牙四类。切牙位于口腔前部，左、右、上、下共8个，邻面观牙冠呈楔形，颈部厚而切缘薄，主要功能是切断食物，为单根。尖牙俗称犬齿，位于口角处，左、右、上、下共4个，牙冠仍为楔形，切缘上有一突出的牙尖，主要功能是穿刺和撕裂食物，为粗壮而长大的单根。双尖牙又名前磨牙，位于尖牙之后、磨牙之前，左、右、上、下共8个，牙冠呈立方形，有一个咬牙合面，其上一般有双尖，下颌第二双尖牙有三尖者，主要功能是协助尖牙撕裂食物及协助磨牙捣碎食物，牙根扁，也有分叉者。磨牙位于双尖牙之后，左、右、上、下共12个，牙冠大，呈立方形，有一个宽大的咬牙合面，其上有4～5个牙尖，主要功能是磨细食物，一般上颌磨牙为三根，下颌磨牙为双根。

根据牙齿在口腔内存在的时间分为乳牙和恒牙。乳牙在出生后7～8个月开始萌出，2。5岁左右乳牙全部萌出，共20个。6、7岁至12、13岁，乳牙逐渐脱落而为恒牙所代替，此期称为替牙时期或混合牙列。因此乳牙在口腔内的时间为5～10年。2。5～6岁左右为乳牙牙合时期。恒牙是继乳牙脱落后的第二副牙列，非因疾病或意外损伤不会脱落，脱落后再无牙齿可萌出代替。第一恒磨牙自胚胎4月开始发育，6岁开始萌出，是最先萌出的恒牙，不替代任何乳牙。12～13岁后乳牙全部脱落后，称为恒牙牙合时期。