五篇高三英语英文教案

高三英语英文教案1

教学目标

Teaching aims and demands

本单元的教学目标 是使学生掌握表示判断和个人看法的常用语句，学会使用现在完成时的被动语态。能利用职权课文中所提供和信息，对比民航在购买计算机管理系统前后的情况，进行描写或表述。

1)Important vocabularies

damage, waste, pollute, fit, room, turn---into, cattle, cause, limit, in place, blow away, sight, present, pour, die out, in danger, no more than, purpose, go off, measure, point to, joy

2)Daily expressions

What was the conference like? (What do you think of /about ---? How do you like ---? How about ---?)

It’s a good idea. (I agree with you. That’s quite true. )

We’ve got to do something about pollution.

What else did you hear about at the meeting?

If ---, ----.

3) Useful phases

It was called ---.

That’s a problem we Chinese must pay special attention to.

It won’t be fit for us to live in.

Many of the injured lost their sight.

A lot of disease are present in the water.

The waters of this great lake.

In 1989 an oil tanker hit a rock off the northwest coast of Alaska.

The most important one is the part that humans have played.

First, ---. Second, ----.

In all there are probably no more than a total of 400 tigers left in China.

Last Monday our class went on an organized trip to a forest to study the wildlife.

He was busy measuring a plant and taking photographs of it.

To my great joy, ---.

4) Grammar

The Past Particle as Predicative and Attribute

教学建议

能力训练

1.通过口头练习，学会日常生活中各种表达自己观点和看法的方式。

2.学会简单的通过表面现象分析内在缘由, 并用现实的事例进行应证，初步掌握这种文体的写作技巧。

3. 通过35课的学习可以简单地描述一个完整的事件。

德育渗透

1.通过课文的学习，使得学生深层地了解地球环保这一重要主题, 让他们懂得地球环保不是一个和几个方面的事情, 而是随时随地, 方方面面, 彼此互相联系和沟通,并且影响着我们人类的生活的大问题。

2.通过对于环保的了解,使同学们的意识增强, 认识到环境污染的严重危害性和从自身做起保护环境的必要性。

师生互动活动

Lesson 33：口头练习：对话交际功能——日常生活用语(给出自己的观点和看法)。

Lesson 34：学生扮演新闻记者采访土壤沙化的当地的居民,印度的受伤的病人, 国家的环保机关的负责人询问有关课文的信息。另外可以让学生扮演俄罗斯的环保专家。

Lesson 35：学生扮演国家历史博物馆的讲解员同时其他学生可以作为参观者询问问题,了解某种动物的发展兴衰史。

Lesson 36：口头,笔头练习：讨论个别环保问题并汇报写出一篇小论文。

口语建议

可以让学生们就西北某一贫困林区毁林种庄稼的做法发表正反两方面的讨论，运用所学的口头的表达方式。

语法建议

可以让学生们将34和35课课文的有关过去分词作定语和表语的结构挑出，写在黑板上用学生找的现实的课文原例分析语法。

教材分析

从本单元的对话来看，主要是学习如何用英语表达出自己的观点和看法, 是同意还是不同意。如同意对方的观点: I think so. I agree completely. I’m with you. That’s a good idea---. I think it is great. 如果不同意: I dont know about that. I don’t think so. Sorry, but I disagree. I know what you mean, but don’t you think ---. I see your point, but I think ---. You’re right, but I think---.

同时注重 damage, pollute, desert, in place, limit, fit, present, pour, die out, measure, go off, point to, to one’s joy 等重点词汇和短语在本单元中学习，本单元中的阅读课主要内容是通过列举如:人为污染地球的土地,空气和水资源以及自然界对人类的报复; 动物界遭到人类的侵害,造成了生态不平衡等事例, 而达到警醒同学和世人,让同学们从小就培养一种环保意识, 维护环境生态的平衡。同时在这里运用了重点语法知识，Past Particle形式充当表语和定语的用法。

重点知识讲解

1. It was called “Saving the earth” and it was all about the damage that is being caused to the world.

1) It was called(believed, thought, considered, known, said ---) that --- 可以看成是主语从句，真正的主语后致，it是形式主语。可以翻译成：据说---, 据认为---。

It is believed that the troops have already crossed the border.

据说军队已经越过边境。

It is known that he is honest.( He is known to be honest.)

听说他是一个诚实的人。

1) damage

n. (不可数) 损坏，损害

The earthquake caused great damage.

地震造成巨大的损失。

When she sees the damage that you have done she will be mad.

当她看到你所造成的损失，她会发疯的。

vt. 损坏

A heavy rain came down and damaged the crops. 一场大雨突至，损坏了庄稼。

Her heart was slightly damaged as a result of her long illness.她长时间的疾病造成了她的心脏受到了轻微的损害。

2. We listen to lectures about pollution, agriculture, nuclear waste, radiation and so on.

waste

vt. 浪费

1) Mother told me not to waste money. 母亲不让我乱花钱。

2) Don’t waste time playing computer plays.不要浪费时间打电脑游戏。

waste something on something/in doing something 用法与spend类似，可以让学生记成“双费(浪费和花费)”。

n. (通常不可数) 浪费, 废物

1) This waste of good food should not be allowed. 浪费食物是不允许的。

2) Where do you put your kitchen waste? 你把厨房的废物放在哪里?

3) It’s a waste of money to buy the book. 买那本书是浪费金钱。

a waste of time/money/energy是固定表达，同a wonderful education类似。

3. It won’t be fit for us to live in.

fit

adj. 适合于---的。 be fit for something:适合某事

1) He isn’t fit for the job. 他不适宜此工作。

2) These shoes are not fit for me. 这些鞋不适合我。

3) The house isn’t fit for you to live in. 这间房子不适合你居住。

be fit for somebody to do something:某人适合做某事

4) This water is fit for drink. 这种水可以喝。

5) It’s not fit for you to talk like that.你这样谈话是不得当的。

adj. 健康的，精力充沛的

6) Exercise keeps you fit. 体育运动使你保持健康。

vt. 对--- 适合，符合，适宜合适，强调大小、尺寸

7) This jacket fits me well. 这件夹克适合我。

8) The key doesn’t fit the lock. 钥匙与锁不符。

9) This theory fits facts. 这条理论适合实际。

vi. 合适

10) The shoes fit perfectly. 这双鞋不合适。

11) He doesn’t fit into the team. 他不宜在队中。

fit somebody to do something/fit somebody for something:使某人适合做某事

12)Vocational training will fit them for a good job.

Vocational training will fit them to get a good job. 职业的培训使他们能找到一个好工作。

vt.安装

12) We fitted a new lock on the door. 我们给门安上了一个新锁。

注意suit表示的是颜色样式和款式的合适。

The color of the cloth suits a woman at my wife’s age. 这块布料的颜色适合我妻子年龄的妇女。

Red and black are colors that suit me well.红和黑色对我来说非常合适。

4. The area of desert in the world is growing every year.

desert n.沙漠

1) He drove a car across the desert. 他开车穿越了沙漠。

vt. 抛弃、背弃

2) He deserted his family. 他抛弃了他的家庭。

vi. 开小差

3) The soldier deserted from the army. 士兵们从军队中开小差跑了。

deserted adj. 无人使用的，已废弃的

4) The railway station was deserted. 那个火车站已经废弃不用了。

5. Then one year, the rains fail to come.

fail vi. 失利，失败 fail to do something 做某事没成功

1) She failed to pass all the exams. 她考试全部失利。

fail in something 在某事上没成功

2) He failed in business. 他在事业上一败涂地。

failure n. 失败 在某一方面失利介词用常用in

3) Her failure in the exam made her cry. 在考试中的失利使她痛哭。

6. One suggested answer is for farmers to limit the numbers of their cattle.

limit vt. 限制

1) We must limit our spending. 我们必须限制我们的开销。

2) Mother limits us to eat one cake each. 母亲限制我们只能一人一块蛋糕。

n. 限制

3) The speed limit within the city is 35 miles per hour. 在城市里的限速是每小时35英里。

7. When trees are cut down, there is nothing to hold the soil in place on the hillside.

place in place 在原处

1) She likes everything to be in place. 她喜欢将每种东西放回原处。

2) I hope you will keep the books in place. 我希望你将书放回原处。

in place of somebody:代替某人

3) Will you go in place of me?你是否代替我去?

take place:发生

4) A car accident took place yesterday. 昨天发生了一起车祸。

take the place of somebody:代替某人

5) I’ll take the place of Mr. Wang. 我将代替王先生的位置。

take one’s place:接替某人

6) I’ll take Mr. Wang’s place. 我将接替王先生。

8. However, many of these are dying out.

die out vi.(火)熄灭

1) The fire died out at last. 最后火还是熄灭了。

vi. 绝种

2) This kind of bird is dying out, and we must protect them. 这种鸟类已经正在灭绝，我们应该保护他们。

9. The purpose of the trip was to record all the wildlife and plants that we could find in the forest.

Purpose n. 目的， 通常是可数名词。目的是什么 用介词for.

1) What was the purpose of his visit? 他来访的目的是什么?

2) He came to Beijing for business purpose. 他来北京是有商业目的的。

on purpose: 专门

3) I had no doubt that she did this thing on purpose. 我毫不怀疑她做这件事是有目的的。

10. In the afternoon, we all went off separately to look for new plants.

Go off 动词短语

走开

1) She got angry and went off after she heard what I said. 听到我所说的她一生气离开了。

响起巨大的声音

2) Although the clock went off, he didn’t wake up.尽管闹钟暴响， 他仍然没有起来。

熄灭

3) The lights went off suddenly. 灯突然地熄灭了。

腐败

4) “The milk has gone off .” my mother said, “ and don’t drink it!” 妈妈说道：“别喝那牛奶了，它已经坏了。”

11. He was busy measuring a plant and taking photographs of it.

Be busy doing, keep busy doing sth. 忙于做某事。

We are busy making preparations for the coming exam. 我们正在忙于为即将来到的考试做准备。

measure vt. 测量

1) The policeman measured the speed of the car. 警察测量车速。

vt. 有……的长度，相当于系动词。

2) The room measures 6m long. 这间房子有六米长。

n.计量单位

3) The meter is a measure of length. 米是一种计量单位。

take the measure of something:测量某物的长度

4) I take the measure of the desk following the teacher’s instructions. 我遵循老师的指令测量桌子。

n.手段、方式

5)They took a strong measure to deal with the workers.他们采取了强硬的手段来对付工人。

12. 分词作为形容词时， A. 及物动词中现在分词表示主动，和动作正在进行;过去分词表示被动或动作已完成。 B. 不及物动词中现在分词表示动作在进行，过去分词表示已完成。

例如：A:

There are many wounded soldiers in the battlefield.

My spoken English has greatly improved.

Don’t sit in that broken chair. It’s dangerous.

She is a leading figure in the Party.

Barking dogs seldom bite.

B:

The risen sun, fallen leaves, retired workers, escaped prisoner , a rolling stone, boiling water, boiled water.

另外还有一些假过去分词。如 1)“adj-noun-ed” a warm-hearted man. 2) “数词-noun-ed” The one-eyed man is hiding behind the door. 3) “数词-度量衡名称” a twenty-cent book

分词作表语， 现在分词表示主动正在进行， 过去分词作表语表示被动已经完成。

The day was so charming! The news is encouraging.

The door remained locked. He seemed quite delighted at the idea. The room was packed with people.

高三英语英文教案2

《Unit 1 Art》

教学准备

教学目标

1. 知识与技能目标

(1)通过阅读有关曼哈顿的艺术博物馆加深对博物馆的了解和认识。提高阅读能力同时学习有关介绍博物馆的相关词汇和表达，并能在特定语境中合理运用。

(2)通过扮演导游对感兴趣的博物馆进行介绍，提高学生的英语口头表达能力同时掌握本单元教学目标和要求中的词汇用法。

(3)通过提供相关词汇进行对潍坊本地的博物馆(潍坊风筝博物馆、杨家埠民间艺术大观园)写一个宣传广告，提高学生的英语写作能力。

2. 过程与方法目标

(1)通过展现曼哈顿以及曼哈顿五个艺术馆的相关图片激发学生的学习兴趣，并激发学生头脑中相关的背景知识为节课做热身。

(2)通过阅读课文利用Skimming 和 Scanning阅读技能找到每个艺术馆的地理位置、艺术特色等相关信息，提高分析处理英文信息的能力。通过寻找描述每个艺术馆的关键词培养学生的归纳总结信息的能力，同时为下一个扮演导游介绍艺术馆的活动做铺垫，提供相关的语言词汇铺垫。

(3)通过提供相关词汇进行对潍坊本地的博物馆(潍坊风筝博物馆、杨家埠民间艺术大观园)写一个宣传广告，提高学生的英语写作能力。

3. 情感、态度、价值观目标

通过学习，使学生了解世界的艺术馆，培养学生的文化意识和对艺术的兴趣。同时激发学生对家乡的自豪感和热爱之情。

教学重难点

教学重点：阅读课文、运用文中相关词汇进行说和写的活动以提高学生读、写、说的能力。

教学难点：在说和写的过程中如何运用相关词汇和表达方式来正确、准确、有效的介绍各个艺术馆的特点。

教学过程

(一)展示学习目标与小组评价规则

(二)“导入”

展示曼哈顿的相关图片，展示课文中出现的5个艺术馆的图片及名字。

(三) Fast reading

快速扫读课文

(四)Detailed Reading: 详细阅读

(五)Challenge your speaking(口语能力提升)

提供参考词汇： Welcome to …

This museum is located in…

It displays(展出) art works in… centuries of …countries, including …

It will appeal to…

You shouldn’t miss…

(六)Challenge your writing (英语写作能力提升)

Watch the videos and then write an advertisement to introduce one of the museums in Weifang. within80 words

写作参考词汇：潍坊世界风筝博物馆(Weifang World Kite Museum)

杨家埠民间艺术大观园(Yangjiabu Folk Art Museum)

kite 风筝 wood-print new year pictures木板年画 be located in 位于

…is famous/well-known for …因…而出名 it displays/shows…展出

Here you can enjoy… 在这里你可以欣赏到… artist 艺术家 appeal to 吸引 tourist 游客 it’s well worth a visit 很值得参观

(七)成果展示

个别学生优秀作文展示

(黑板展示)

展示作文评分细则

教师点评

课后习题

测评练习

测评一：

从文中找出相对应的短语和句子。(预习测评)

1.宁愿做…

2.对…偏爱

3.值得一去

4.吸引

5.在于

6.不仅仅是

7.向…引进(介绍)

8.生活方式

9.贮存于

10. 入场费(门票)

11. 一个…的收藏

12.每两年

13.健在的艺术家

14.亨利.克莱.弗利克是纽约的一位富豪，于1919年去世，把他的房子、家具和艺术收藏品全部留给了美国人民。

15. 这家博物馆展示的不只是看得见的艺术之美，它还向你介绍了古代的生活方式。

16. 馆内没有永久展出，展品都是随时更换的。

测评二

Writing (写作测评)

Write an advertisement to introduce one of the museums in Weifang. within80 words

高三英语英文教案3

《Unit 3 A taste of English humour》

教学准备

教学目标

Teaching Objectives

1. Students are able to learn more about nonverbal humour as well as Charlie Chaplin through network-based.

2. Students are able to get the gen eral idea and detailed information of the passage by skimming, scanning as well as interpreta tion and appreciation.

3. Students will learn to face difficulties in life with optimism and humour as well as learn to cooperate with others in groups.

教学重难点

Teaching difficult points

1. How to guide students to search for and sort out related information according to the assigned task through the Internet.

2. How to cu ltivate students’ learning ability through teamwork based on network.

Teaching important points

1. Help students to get the general idea and detailed information of the text effectively by skimming and scanning.

2. Help students to analyze the reasons for Charlie Chaplin’s success by interpreting the key sentences and get them inspired.

教学过程

Step 1

Lead-in(3 mins)

1.Students’ Activities：

2.The Purpose of Activities

Students are to appreciate a video clip performed by Mr. Bean.

Students will be guided to acquire the form of nonverbal humour in a vivid way,

thus eage r to learn about the main character of the text with interest.

Step 2

Network-based Interactive Learning(25 mins)

1.Students’ Activities

(1).Students are divided into five groups to search for and sorted out the related information according to the assigned task online

(2)A representative of each group is to share the information with the others.

2.the Purpose of Activities

Students will develop their ability to effectively sort out information on the Internet throug h group cooperation as well as feel a sense of achievement by their oral presentation.

Step3 Text-based Reading(17 mins)

Students’ Activities 1. Students are to read the text quickly, and then answer the questions according to the text. 2. Read Paragraph 3 carefully, and then answer the question ---Why did “the little tramp”become Charlie Chaplin’ famous character ?3. Read Paragraph 4 and fill in the blanks

。4. Find out the sentences that can account for Charlie Chaplin’s success from the text.

2.The Purpose of Activities

(1)Students will get the general idea as well as the structu re of the text by skimming.

(2)Students will get the detailed information and have a deeper understanding of the text.

(3) Students will get inspired while analyzing the secret to Charlie Chaplin’s success by interpre ting and appreciating some key sentences in the text.

课后习题

Step 5 Homework

1. Students are to read the text carefully again and underline the phrases and sentences difficult to understand after class.

2. Write a summary (about 130 words).

高三英语英文教案4

《Unit 2 Working the land》

教学准备

教学目标

(1)知识目标：让学生通过阅读课文更多地了解我国的农业科学家袁隆平的科研成果及其影响。

(2)能力目标：让学生进一步使用恰当地阅读方式与技能，如略读(skimming)，快速阅读(fast reading)，细读(close reading)等

(3)情感目标：让学生不但学习袁隆平的科研精神，更要学习他不计较名利，踏踏实实的生活态度。

教学重难点

1.阅读课文更多地了解我国的农业科学家袁隆平的科研成果及其影响。

教学过程

1. 话题的引导。(Pre-reading)

1).开头通过设计了一首熟悉的诗歌，让学生知道话题---farming.

2).涉及到提高产量从而解决世界饥荒问题，从而引出本节课的中心话题--伟大人物袁隆平。

2. 跟读与阅读 完成导学案练习

贯彻目的与困难策略，指导学生根据不同的阅读目的，在阅读的不同阶段，灵活使用各种阅读策略，捕捉文章主要信息，理解作者的写作意图，突破本文的教学重点与难点。采用整体语言教学法和任务型语言教学法。

1)、通过阅读训练，引导学生如何利用略读(skimming)的方法把握文章的大意，侧重培养快速阅读理解能力和文章中心把握能力。

2)、精读各个段落语段，侧重培养快速捕捉文章重要细节的能力和猜测生词的能力，学会欣赏文章中的优美句子。

3： 阅读过程--浅层次阅读。(Reading I)

1). 其中关于人物的基本信息中，通过设计了一个信息表格的浅层次阅读练习，对文中人物有了初步了解。

2). 关于他的梦想，书本上描写得非常生动，我让班里有艺术特长的学生画了一幅漫画，利用画面反映课文第四段所描述的内容，同时用第一人称配了声音效果。

4. 阅读过程--深层次阅读。(Reading II)

在处理了一些简单信息之后，阅读人物最重要的是要读出人物不同于其他人的成就以及值得学生学习的一些可贵品质。就这两方面的内容，设计了一棵树的形象，引导学生去寻找袁隆平作出的成就以及他身上拥有的可贵品质。

5.知识点的处理：由句子的分析带出语言点，记住句子，记住了单词用法

课后习题

一、单词拼写

1. ____________ vt. & vi. 斗争; n.努力

2. ____________ adj. 感到满意的

3. ____________ n.自由; 自主

4. ____________ vt. & vi. 配备; 装备

5. ____________ n. 产量, 输出量

6. ____________vt. 输出 n.出口

7. ____________vt. 搞乱, 使糊涂

8. ____________ n. 补给; vt.提供

9. ____________ adj. 适当的, 相配的

10. ___________vt. 使膨胀 vi. 发展

二、单词运用

1.We had a ___________(努力) to stop the criminal.

2. The document will be _____________ (传阅) to all members.

3. I’ll type your report if you’ll baby-sit in e_________.

4. Our farm ___________ the market with fruits and vegetables.

5. We should s__________ the results of the exam briefly and report to the headmaster.

6. Sydney’s population _____________ rapidly in the 1960s.

7. He has a ____________ (晒黑的) face and bright eyes.

8. The plane _________ speed as it was approaching the airport.

9. The workers there worked _______ crazy, with only thirty minutes’ break at noon.

10. He __________ (耕作) the farm with great success.

Comprehending：Paraphrase these sentences.

1. At that time, hunger was a disturbing problem in many parts of the countryside

2.Using his hybrid rice, farmers are producing harvests twice as large as before.

3. Thanks to his research, the UN has more tools in the battle to rid the world of hunger.

4.He would much rahter keep time for his hobbies.

Consolidation Exercise;

1._____ your generous help, or I will not overcome the difficulty.

A.Thanks to B. Because

C. Thanks for D. Thank to

2. It is so_______ that he is always making noises.

A. disturbed B. disturbing

C. disturb D. disturbs

3. He missed the bus, for ________ he came late for work..

A. whom B. that C.where D. which

4.你必须戒除掉自己吸烟的坏毛病。

5. 满意于学生的成绩，他如释重负的笑了。

6. 他宁愿在家里看电视也不愿意打篮球。

高三英语英文教案5

《Fit for Life》

Fit for Life

新课标单词

historian n. 历史学家 recipe n. 处方;食谱，菜谱 physician n. 医生，内科医师

bark n. 树皮;(狗)叫，吠 vi. (狗)叫，吠 chemist n. 药剂师;化学家

trial n. 试用;试验;考验 tablet n. 药片;写字板，书写板

standardize vt. 使符合标准，使标准化 best-selling adj. 畅销的

painkiller n. 止痛药，镇痛剂 author n. 作者 heart attack 心脏病发作

thin vt. & vi. (使)变稀，(使)变薄，(使)变淡;(使)变细

block vt. 阻塞，阻挡;妨碍 length n. 长度 contemporary adj. 当代的;同时代的

Scottish adj. 苏格兰的 note vt. 发现，注意到;记录 transparent adj. 透明的

application n. 应用，运用;申请 name vt. 命名，给……取名

unable adj. 不能的，不会的 chemical adj. 化学的 purify vt. 使纯净，净化，提纯

quantity n. 量，数量 widespread adj. 普遍的，普及的，广泛的 lung n. 肺

mass adj. 批量的，大量的，大规模的;群众的，民众的

n. 团，块，堆;较大部分，主体部分;体积，大小，群众，人群

rapidly adv. 迅速地，快速地 powerful adj. 效力大的，强效的

wonder adj. 非凡的，奇妙的，奇特的，神奇的

n. 奇迹，神奇;奇观;惊奇，惊讶

millions of 数百万的，大量的 relief n. 减轻，缓解;轻松，宽慰;救济，救助

potential adj. 潜在的，可能的 enquiry n. 询问，咨询 ward n. 病房

fundamental adj. 基础的，根本的;重要的，至关重要的

handful n. 少数，少量;一把 annual adj. 每年的，一年一次的

arrangement n. 安排;排列 receptionist n. 接待员，招待员

pleasure n. 愉快，快乐;乐事 eyesight n. 视力 adjustable adj. 可调节的

magic adj. 有魔力的，不可思议的，魔术的 needle n. 针 art n. 技艺，技术

sharp-edged adj. 有锋利边缘的 swollen adj. 肿胀的 arrowhead n. 箭头;箭头状物

sharp adj. 锋利的锐利的;尖的;突然的，急转向的;尖刻的，辛辣的;灵敏的，敏锐的

fine adj. 细的，纤细的 point n. 点，位置;尖端;要点;分数

insert vt. 插入;嵌入 symptom n. 症状 function n. 功能，作用

heartbeat n. 心跳 addiction n. 上瘾，沉溺，入迷 overeating n. 过量饮食

relieve vt. 减轻(病痛、忧虑、负担等)，缓解;救济，救助 unclear adj. 不清楚的

课文出现短语

1. keep us healthy 2. open up 3. carry out 4. give up 5. come true 6. figure out

7. go wrong 8. put off 9. put up with 10. make out 11. call back 12. look out for

13. at certain points 14. find out 15. if so 16. recommend doing

17. in contemporary society 18. in large quantities 19. trun into

20. be fundamental to (doing) 21. a disease called malaria 22. look into

23. look down upon 24. put through 25. come up 26. remind sb to do

27. be based on 28. block from doing 29. focus on 30. reduce the risk of

31. try out 32. due to 33. in addition to 34. have an influence on

35. leave behind 36. ask for 37. set up 38. put off

39. take measures to do 40. let … out of 41. be connected with

一.单词应用

根据单词的首字母或汉语意思填写正确单词，注意形式变化。

1. A p____________ is a person who has general skills to treat physical problems.

2. Penicillin was d___________ in the mould that grew on a special transparent jelly.

3. He is the a__________ whose books are best-selling this year.

4. Stoke is a type of serious illness when blood vessels in the brain b_____ suddenly