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8B Unit 3serve; service; servant:serve v. 意为：“为…服务；待客”。
例如：They served the guests a wonderful dinner. 他们以盛宴招待客人们。
service n. 意为“服务”。
例如：The train service to the capital is very good. 去首都的火车服务设施非常好。
servant n. 意为“仆人；佣人”。
例如：Fire and water may be good servants, but bad masters.(谚语)水火是忠仆，用之不慎成灾主。
electric; electrician; electricity:electric adj. 意为“发电的；由电产生的；电动的”。
例如：They build electric automobiles. 他们制造电动汽车。
electrician n. 意为“电工”。
例如：Master Wang is an electrician. 王师傅是电工。
electricity n. 意为：“电”。
例如：The power station supplies electricity to this area. 这个点站供应这个区域的电。
explain; explanation:explain v. 意为“解释；说明”。
例如：Can you explain why you were late? 你能解释一下你为什么迟到吗？explanation n. 意为“解释；解说；说明”。
例如：The only explanation for his behaviour is that he is mad.对他行为的唯一解释就是他疯了。
visible; vision；invisible:visible adj. 意为“看得见的；显著的；明显的”。
例如：Air isn’t a visible object. 空气不是可见物体。
第 1 页8B Unit 3 ElectricityP31 1. energy n. 能量;活力;精力—energetic a. 精力充沛的e.g. He is full of energy. =He is energetic.2. electricity n. 电—electric a. 电的；用电的—electrical 关于电的—electronic a. 电子的---electrician n. 电工；电器技师e.g. Electricity is very important to us. 电对我们很重要。
每一件电器名称都用electric ，如：electric lights 电灯/ fans 风扇/ kettles 水壶/ rice cookers 电饭煲/ iron ….电熨斗电器设备总称：electrical appliances =electrical machinese.g. There are many electrical appliances in my home. 带电子的用electronic: an electronic watch an electronic dictionary 电子词典/ calculator P321. change … into …=turn …into …v. 把……变成….. --- changeable a. ---exchange v. 交换2. different kinds of energy n. 不同种类的能量---d ifference (s) n.---be different from3. kind n. 种类=sort =type a . 友善的；仁慈的be kind to sb.=be friendly to sb.（宾格）4. heat energy n. 热能moving energy n. 动能5. move v. 移动；搬动；使感动---moved a. 被感动的---moving a. 感人的e.g. The film was so moving that we were moved.这部电影如此感人，我们都被感动了。
八年级第二学期牛津英语知识点梳理及配套练习Unit 3 Electricity知识点梳理：I 词组1one evening 一天晚上2get me a packet of electricity 给我带一包电3go out 出去4at last 最后5buy it in packets 一包包地买6look foolish 看上去很傻7flow through a wire 流过电线8measure the amount you use 测量你使用的电量9get a bill for 得到一张……的账单10in a way 在某种程度上11much more dangerous than …比……危险得多12be careful with 小心对待13look like 看似……样14scratch one’s head 挠头15change … into …把……变成……16think of 想一想；想出来17 a light bulb 电灯泡18come from 来自于19different forms of energy 各种能量20be connected to 被连接到……21bury under the street 埋在路下22 a power station 发电站23come back 回来24May I have … , please? 我可以……吗？25on his face 在他脸上26Here it is. 它在这儿27Didn’t you know that? 你不知道吗？28switch off 关上II. 词性转换1.dangerous (a.) 危险的danger (n.) 危险2.servant (n.) 仆人serve (v.) 服务service (n.) 服务3.electricity (n.) 电electric (a.) 电的electrical (a.) 有关电的4.foolish (a.) 愚蠢的fool (n.) 傻瓜/（v.）愚弄5.monthly (ad.) 每月一次month (n.) 月份6.explanation (n.) 解释explain (v.) 解释7.careful (a.) 小心的care (n. / v.) 关心carefully (ad.) 小心地careless (a.) 粗心的8.invisible (a.) 看不见的visible (a.) 看得见的9.change (n. / v.) 变化changeable (a.) 多变的10.different (a.) 不同的difference (n.) 不同点11.power (n.) 力powerful (a.) 强大的12.politely (ad.) 有礼貌地polite (a.) 有礼貌的impolite (a.) 没礼貌的13.contain (v.) 包含container (n.) 容器14.clear (a.) 清楚的clearly (ad.) 清楚地III. 语言点1. I’m going to buy a packet of sweets.a packet of 意为“一包；一袋”。
上海牛津版八年级下册同步讲义Unit 3 Electricity1. servant n. 仆人；佣人e. g. Fire and water may be good servants, but bad masters. [谚]水火是忠仆，用之不慎成灾主。
A politician should be a servant of the people. 政治家应当是人民的公仆。
【知识拓展】 serve v. 服务，待客e.g. They served the guests a wonderful dinner. 他们以盛宴招待客人们。
service n. 服务e. g. The train service to the capital is very good. 开往首都的火车服务设施非常好。
注：除了跟学生讲解servant的三个词性转换外，还要告诉学生serve 是及物动词，后面直接跟sb.2. trick v. 欺骗；坑人e. g. Her tricked me into giving him the money. 他哄骗我给了他钱。
（常与out of连用）骗走，恶作剧e.g. His partner tried to trick him out of his share. 他的合伙人企图骗走他的股份。
【知识拓展】 trick n. 诡计；骗术，花招e. g. I can do magic tricks. 我会变魔术。
The children played a trick on their teacher. 孩子们捉弄了他们的老师。
注：根据同类短语讲解trick，例如：play a trick on sb. /make jokes about sb.开某人的玩笑3. electricity n. 电e.g. The power station supplies electricity to this area. 这个电站供应这个区域的电。
上海牛津版八年级下学期英语词组知识点梳理Unit 1be interested inbiggest and oldestliving thingsmake streets more beautiful and less noisy on the end ofcome fromsupposeenjoy breathing pure, cool airthank…fortake…fromharmful gasesrelease…intoproduce enough oxygenkeep …alive and healthycool the airas well asnatural air conditionersrundo the job ofknow a lot about sthattack a treewarnprotect themselves by doing sth join…togetherpass…tocommunicate with one anotherbe in dangercut downreplacehardlydestroyexchangenaturemainUnit 2pour…intovanish down the drainturn…offlook aroundsound impatient/puzzledIt’s not easy for me to get here. comfortablycarry…torelaxtravel a long wayIt was time to get cleaned up. give...a thorough cleaning add…towait…untilthe end of the journey remember not to do sthpreciousWhat do you mean by doing sth? no replaycome out ofto restordinarymanufactureequipmentUnit 3servanta packet of sthtricklook foolishflow through a wiremeasurethe amount ofmonthlyin a wayexplanationmuch more dangerousbe careful withCan you tell me what it looks like? Be invisiblechange…intodifferent forms of energycome into our flatbe connectedto call…sth politelycontainproduceswitch offlockencouragebehavepolitecustomerUnit 4hold a meeting/be at the meeting decide to do sththe chief editorsuggest that sb (should) do sth vote forelect sb. to betake charge ofought to do sthask for suggestionhave experiencebe secretary oftake notesthe other threebe responsible fortalk…overamongmake a list of sthpublish the paperbe free to pay for sthconsiderbrieflyask whether…have an ideathink about…a bit longermake a decision aboutagree to do sthconcludearrange to do sthin one week’s timeagree onin alltalentgather delightedshamedesigncomplainUnit 5belong toas soon aswalk into someplacebook a roomYou’re welcome.allowsound like…interruptat oncebothlead sb.Personally to…before doing sththe location of the fireexitsafetydescribe sth to sbin one own wordsbe asleepsmell smokego offmust be outsidethe phone was deadalonglay on the floorbesideseem likemoments later/seconds later be safesave one’s lifelendtake caremindlook outwatch outUnit 61. now that: since2. be behind sb3. think about doing sth.4. go abroad国外/ aboard5. why not do sth/Why don’t sb. do sth.6. spread one’s wings7. one of the most popular tourist destinations8. such as / fore example9. wide, tree-lined streets10. the same size as / as big as11. attractions / attractive12. an hour away from/ how far13. the center of Paris14. offer to do sth.15. go on to do sth./ go on doing sth.16. do it without doing sth17. enable…to / be able to do sth. /ability (n.)18. travel…from…to…19. grow crops20. make + adj./ make sb. do sth21. excellent : very good22. used to do sth. 过去常常做某事/ be used to doing习惯于做某23. be famous for24. the influence of ./ have an influence on25. in some way 26. provide sb. for sth./ provide sth. for sb.27. a leader in art and culture ( led- leading)28. a lot of young students from differentcountries go to France29. to further one’s study (why?)30. film festivals, exhibitions and concerts31. throughout the world/all over the world Unit 71. be at home/ be at work2. a boring man/ make me bored3. on the site4. walk on a narrow plank5. scared/scary6. on one’s own: by oneself7. be pleased with (pleasing, pleasure, pleasant)8. be cross/ angry9. pay attention to10. scold sb 11. put sb in detention 12. help sb in every way13. love chatting with sb (talk with)14. be puzzled by sth (puzzling)15. Pretend to do sth.16. concern about17. accept - acceptable18. express -expression19. honest- honesty-dishonest20.patient-patience-impatient-patiently-impatiently最新文件---------------- 仅供参考--------------------已改成-----------word文本--------------------- 方便更改赠人玫瑰，手留余香。
学员编号：年级：初二课时数：学员姓名：辅导科目：英语学科教师：授课类型T Unit3（牛津8下）基础知识梳理星级★★★教学目标1、使学生能够基本掌握本单元中的基础词汇及重要句型；2、使学生熟练运用本节课所学的知识。
授课日期及时段T同步-U3基础知识梳理（建议2-5分钟）ElectricityFor other uses, see Electricity (disambiguation). "Electric" redirects here. For other uses, see Electric (disambiguation).Lightningis one of the most dramatic effects of electricity.Electricity is the set of physical phenomena associated with the presence and flow of electric charge. Electricity gives a wide variety of well-known effects, such as lightning, static electricity, electromagnetic induction and the flow of electrical current. In addition, electricity permits the creation and reception of electromagnetic radiation such as radio waves.In electricity, charges produce electromagnetic fields which act on other charges. Electricity occurs due to several types of physics:•electric charge: a property of some subatomic particles, which determines their electromagnetic interactions.Electrically charged matter is influenced by, and produces, electromagnetic fields.•electric current: a movement or flow of electrically charged particles, typically measured in amperes.•electric field(see electrostatics): an especially simple type of electromagnetic field produced by an electric charge even when it is not moving . The electric field produces a force on other charges in its vicinity. Movingcharges additionally produce a magnetic field.•electric potential: the capacity of an electric field to do work on an electric charge, typically measured in volts.•electromagnets: electrical currents generate magnetic fields, and changing magnetic fields generate electrical currentsIn electrical engineering, electricity is used for:•electric power where electric current is used to energise equipment•electronics which deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries. Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry and society. Electricity's extraordinary versatility as a means of providing energy means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is the backbone of modern industrial society.The word electricity is from the New Latin ēlectricus, "amber-like"[, coined in the year 1600 from the Greek ήλεκτρον(electron) meaning amber, because electrical effects were produced classically by rubbing amber.批注：通过阅读这篇短文，让学生了解electricity，引入今天的主题。
8B Unit 3 ElectricityP311. energy n. 能量;活力;精力—energetic a. 精力充沛的e.g. He is full of energy. =He is energetic.2. electricity n. 电—electric a. 电的；用电的—electrical关于电的—electronic a. 电子的---electrician n. 电工；电器技师e.g. Electricity is very important to us. 电对我们很重要。
每一件电器名称都用electric，如：electric lights 电灯/ fans 风扇/ kettles 水壶/rice cookers 电饭煲/ iron….电熨斗电器设备总称：electrical appliances =electrical machinese.g. There are many electrical appliances in my home.带电子的用electronic: an electronic watch an electronic dictionary 电子词典/ calculator P321. change… into…=turn…into…v. 把……变成….. --- changeable a. ---exchange v. 交换2. different kinds of energy n. 不同种类的能量---difference(s) n.---be different from3. kind n. 种类=sort =type a. 友善的；仁慈的be kind to sb.=be friendly to sb.（宾格）4. heat energy n. 热能moving energy n. 动能5. move v. 移动；搬动；使感动---moved a. 被感动的---moving a. 感人的e.g. The film was so moving that we were moved.这部电影如此感人，我们都被感动了。
8B Unit 3 Electricity4. someone pron. 某人；有人---anyone 任何人–no one 没有人P31Somebody pron. 某人；有人---anybody任何人---nobody没有人5. someone else 其他人能量1. energy n. ;活力;精力—energetic a. 精力充沛的6. something pron. 某物；某事---anything 任何东西---nothing 无；没什么nothing =not anythinge.g. He is full of energy. =He is energetic.7. 不定代词something；anything；nothing；放在形容词前面 2. electricity n. 电子的electronic a. —electrical 关于电的—电—electric a. 电的；用电的 e.g. I have something important to tell you. 我有件重要的事要告诉你。
---electrician电工；电器技师n.Are there anything living on the moon? 月球上有活的东西吗？ e.g. Electricity is very important to us. 电对我们很重要。
There is nothing interesting in today's newspaper. 今天的报纸上没有什么有趣的事。
/风扇/ kettles 水壶，如：每一件电器名称都用electric electric lights 电灯/ fans8. do nothing =don't do anything e.g. They found nothing in the cave. =They didn't find anything in rice cookers 电饭煲/ iron….电熨斗the vave. 他们在山洞里没有找到任何东西。
—－可编辑修改，可打印——别找了你想要的都有！精品教育资料——全册教案，，试卷，教学课件，教学设计等一站式服务——全力满足教学需求，真实规划教学环节最新全面教学资源，打造完美教学模式8BUnit3牛津英语知识点梳理及配套练习2011-08-25 17:55:58| 分类：8BUnit3 Electric|举报|字号订阅八年级第二学期牛津英语知识点梳理及配套练习Unit 3 Electricity知识点梳理：I 词组1one evening 一天晚上2get me a packet of electricity 给我带一包电3go out 出去4at last 最后5buy it in packets 一包包地买6look foolish 看上去很傻7flow through a wire 流过电线8measure the amount you use 测量你使用的电量9get a bill for 得到一张……的账单10in a way 在某种程度上11much more dangerous than …比……危险得多12be careful with 小心对待13look like 看似……样14scratch one’s head 挠头15change … into …把……变成……16think of 想一想；想出来17 a light bulb 电灯泡18come from 来自于19different forms of energy 各种能量20be connected to 被连接到……21bury under the street 埋在路下22 a power station 发电站23come back 回来24May I have … , please? 我可以……吗？25on his face 在他脸上26Here it is. 它在这儿27Didn’t you know that? 你不知道吗？28switch off 关上II. 词性转换1.dangerous (a.) 危险的danger (n.) 危险2.servant (n.) 仆人serve (v.) 服务service (n.) 服务3.electricity (n.) 电electric (a.) 电的electrical (a.) 有关电的4.foolish (a.) 愚蠢的fool (n.) 傻瓜/（v.）愚弄5.monthly (ad.) 每月一次month (n.) 月份6.explanation (n.) 解释explain (v.) 解释7.careful (a.) 小心的care (n. / v.) 关心carefully (ad.) 小心地careless (a.) 粗心的8.invisible (a.) 看不见的visible (a.) 看得见的9.change (n. / v.) 变化changeable (a.) 多变的10.different (a.) 不同的difference (n.) 不同点11.power (n.) 力powerful (a.) 强大的12.politely (ad.) 有礼貌地polite (a.) 有礼貌的impolite (a.)没礼貌的13.contain (v.) 包含container (n.) 容器14.clear (a.) 清楚的clearly (ad.) 清楚地III. 语言点1. I’m going to buy a packet of sweets.a packet of 意为“一包；一袋”。
第三讲Unit3 Electricity上海牛津沪教版八年级(下)同步讲义Unit3 Electricity适用学科初中英语适用年级初中二年级适用区域上海课时时长（分钟）120分钟（一对一）知识点知识点1：本单元词汇知识点2：词组知识点3：句型知识点4：情态动词的用法知识点5：宾语从句知识点6：系动词的用法教学目标知识：学生能够基本掌握8年级上册Unit3中的词汇、词组、句型及语法。
方法：牢记各个知识点的用法，归纳总结异同点，通过习题加强巩固。
能力：熟练掌握各种词汇的用法；具备准确判断词性及转换的能力；熟练掌握情态动词的用法；熟练掌握宾语从句的句序；熟练掌握系动词的用法；教学重点词性转换；宾语从句；情态动词；教学难点宾语从句的句序教学过程一、课堂导入教师讲述一个与本节课题目有关的英文小故事，引出今日所要讲解的知识点，然后让学生简单梳理一下所涉及的问题，带着问题学习本节课的内容。
二、复习预习教师引导学生复习上节课学的重点内容，检测单词的用法，（以提问、回顾的形式进行），针对上节课的作业进行讲评、订正、答疑，并通过英文小故事导入本节课所要学习的新知识。
三、知识讲解1. 知识点一：重点单词1）servant [ˈsɜ:vənt]【词性】n.【词义】仆人【易混淆点】servant 仆人service 服务serve 提供服务【经典例句】Why is the servant in the title dangerous?为什么标题中的仆人是危险的？2）electricity [ɪˌlekˈtrɪsəti]【词性】n.【词义】电；电能【易混淆点】electricity 电；电能electrical 用电的【经典例句】Can you get me a package of electricity, please?你能给我一包电吗？3）trick [trɪk]【词性1】v.【词义1】哄骗【词性2】n.【词义2】诡计；花招【易混淆点】trick 哄骗；诡计cheat 欺骗【经典例句】I’ve tricked Daisy at last.我最终哄骗了Daisy。
8B Unit 3 ElectricityP311. energy n. 能量;活力;精力—energetic a. 精力充沛的e.g. He is full of energy. =He is energetic.2. electricity n. 电—electric a. 电的；用电的—electrical关于电的—electronic a. 电子的---electrician n. 电工；电器技师e.g. Electricity is very important to us. 电对我们很重要。
每一件电器名称都用electric，如：electric lights 电灯/ fans 风扇/ kettles 水壶/rice cookers 电饭煲/ iron….电熨斗电器设备总称：electrical appliances =electrical machinese.g. There are many electrical appliances in my home.带电子的用electronic: an electronic watch an electronic dictionary 电子词典/ calculator P321. change… into…=turn…into…v. 把……变成….. --- changeable a. ---exchange v. 交换2. different kinds of energy n. 不同种类的能量---difference(s) n.---be different from3. kind n. 种类=sort =type a. 友善的；仁慈的be kind to sb.=be friendly to sb.（宾格）4. heat energy n. 热能moving energy n. 动能5. move v. 移动；搬动；使感动---moved a. 被感动的---moving a. 感人的e.g. The film was so moving that we were moved.这部电影如此感人，我们都被感动了。
6. light energy n. 光能light n. 光; a. 轻的；淡的7. sound energy n. 声能sound n. 声音；voice n. 说话声；嗓音；语态noise n. 噪音8. look foolish a. 看起来傻（look后没有介词，后跟形容词。
look后有介词，后跟副词）9. foolish a. =stupid =silly 愚蠢的---fool v. 欺骗；愚弄n. 傻子April Fool’s Day 愚人节e.g. Don’t fool me. I’m not a fool. I won’t be fooled.不要骗我。
我不是傻子。
我不会被骗的。
It’s foolish of you to trust him. 你信任他是愚蠢的。
10. serve v. 服务；提供—service(s) n.服务—servant n. 仆人；佣人n.serve people /the customers 为人民/顾客服务good services 优质的服务11. someone who does housework for others n. 某一个为别人做家务的人=servant12. danger n. 危险---dangerous a. –more dangerous—most dangerouse.g. Trees are in great danger. 树木正处于极大的危险中。
be out of danger 脱离危险P331. on a cold evening ; on the morning/ afternoon /evening of…在怎么样的早/ 中/ 晚2. buy a card for me =buy me a card buy—bought—bought sell—sold—sold 卖3. a packet of sweets n. 一包糖4. someone pron. 某人；有人---anyone 任何人–no one 没有人Somebody pron. 某人；有人---anybody任何人---nobody没有人5. someone else 其他人6. something pron. 某物；某事---anything 任何东西---nothing 无；没什么nothing =not anything7. 不定代词something；anything；nothing；放在形容词前面e.g. I have something important to tell you. 我有件重要的事要告诉你。
Are there anything living on the moon? 月球上有活的东西吗？There is nothing interesting in today’s newspaper. 今天的报纸上没有什么有趣的事。
8. do nothing =don’t do anything e.g. They found nothing in the cave. =They didn’t find anything in the vave. 他们在山洞里没有找到任何东西。
9. get (=buy) me a packet of batteries =get a packet of batteries for me 给我买包电池10. please v.请；使高兴--pleased a.高兴的--pleasant a.愉快的；令人高兴的--pleasure n.令人高兴的事e.g. Pleased to meet you. I’m pleased with you. 我对你很满意。
The trip was pleasant. It’s a pleasure to talk with you. 跟你谈话是件高兴的事。
11. go out v. 外出；熄灭go–went --gone12. laugh v. 笑；嘲笑---laughter n. 笑声；笑laugh at others 嘲笑别人be full of laughter 充满笑声13. trick v. 哄骗；欺骗n. 诡计；把戏；恶作剧do magic tricks. 玩/ 变魔术play a trick on sb. 捉弄某人14. at last =finally =in the end adv. 最后15. She doesn’t even know what electricity is.她甚至不知道什么是电。
（从句用陈述的语序）16. buy electricity in packets买袋装的电like 喜欢；像—unlike 不像17. Do you know what electricity is? 你知道电是什么吗？（从句用陈述的语序）18. Our physics teacher told us (that) light travels faster than sound. (一般情况下主句和从句的时态要统一，但从句若表示自然现象、科学真理时，永远用一般现在时。
)19. flow through a wire v. 通过电线流动---flowed--flowed20. A meter measures the amount you use. 计量表测（量）出你所用的量。
21. get a bill monthly adv.= every month 每月收到一张账单monthly a. 每月的monthly meeting 月会22. in a way =partly 在某种程度上；从某种意义上来说23. explain v. 解释；说明;讲解---explanation n. explain to sb.e.g. Don’t explain it to me. I don’t want to listen to your explanation.24. bad a. 坏的；严重的—(ill/ badly/ bad) --worse—worst a bad cold 严重的感冒25. although/ though conj. 尽管；虽然（不能与but连用, 但经常跟still, yet 连用。
e.g. Although he was so tired, he still went on working.26. much+比较级=far+比较级：什么什么得多 e.g. much taller 高得多；高很多27. Electricity is much more dangerous than water. 电比水危险得多。
28. 替代词one和ones的用法：one只能代替单数名词(可数名词)。
e.g. I don’t like this cup. I like the blue one.ones替代复数名词。
e.g. Do you want the red apples or the green ones?29. must aux.应该；必须；一定mustn’t 不准；不能30. must be 一定是—can’t be 不可能是31. be careful with sth. 当心/ 小心某物---careless a. 粗心的--carefulness n. 细心be careful with the chemical/ vase 小心这个化学品/ 花瓶32. Can you tell me what it looks like?（从句用陈述的语序）你能告诉我它是什么样的吗？33. 问长相和面貌的句子：e.g. What does Betty look like?/ What is Betty like?/ How does Betty look?34. scratch his head v. 挠挠他的头35. I have never been to America. (改为一般疑问句) ：Have you ever been to America?36. invisible a. ：cannot be seen看不见的；隐形的---visible a. 看得见的；明显地37. different forms of energy 不同形式的能量38. different forms of energy that we can see, hear or feel 我们能看得见、听得到或摸得着的不同能量形式39. hear v.—heard—heard 听见；听到feel v.—felt—felt 感觉40. think of an example 想出一个例子think of 想起；想到；想出—thought--thought41. a light bulb 一个灯泡42. That’s right. 那是对的；说对了That’s all right. 没关系43. Do you know where electricity comes from? 你知道电是从哪里来的吗？（从句用陈述的语序）44. come into our flat =enter our flat 进入我们的公寓---entrance n. 入口45. through thin wires 通过细的电线thin a. 细的；瘦的；薄的—thinner--thinnest46. be connected to thick wires 被连接到粗的电线；和粗电线相连connect =join连接47. bury v. 埋葬---buried--buried48. call the thick wires cables 把这些粗电线称为电缆49. a power station n.发电站power n. 力量；权利---powerful a.强大的；有效的e.g. Knowledge is power. 知识就是力量。
