译林版英语八年级下册第一单元课堂笔记
八年级英语课堂笔记
8B Unit 1 Past and Present
1. the changes to Sunshine Town阳光镇的变化→the changes to… …的变化
change n.变化，常用复数changes。
e.g. Great changes have taken place since 1995.
2. in the southern part of town →in the southern part of…在…的南部→south →southern
east东部→eastern东部的, west →western, north →northern
3. in the past在过去→at present现在→in the future未来；将来，注意这些短语中的介词和冠词。
4. turn the place into a park →turn…into…把…变成…
①Heat turns water into vapor.热使水变成蒸气。
②Turn this sentence into English.
5. play cards and Chinese chess打牌、下象棋，e.g. It’s pleasant to play cards and Chinese chess.
6. water pollution水污染→air pollution空气污染，noise pollution噪音污染(p9)
Water pollution was a problem before.
7. used to dump its waste into water →used to do sth过去常做某事，注意否定式、疑问式的形式
⑴used to do sth →否定式used not to do sth或didn’t use to do sth→疑问式Did sb use to do sth?或Used sb to do sth?
⑵There be和used to合用的形式为There used to be。
根据要求进行句型转换：She used to teach history.
①否定式：She used teach history.或She didn’t teach history.
②疑问式：she teach history?或Did she teach history?
⑴be used to do sth＝be used for doing sth被用于做某事，
e.g. Stamps are used to send letters.＝Stamps are used for sending letters.
⑵be/become/get used to sth习惯于某事，be/become/get used to doing sth习惯于做某事，
①My grandma used to live in the city but now she has got used to the country life.
②Tom is used to getting up early.
8. in some ways在某种程度上；在某些方面→in this way以这种方式
9. feel a bit lonely from time to time →from time to time＝at times＝sometimes有时；不时地
⑴a bit＋形容词原级或比较级＝a little＋形容词原级或比较级，有点…
⑵a bit of＋不可数名词＝a little＋不可数名词e.g. a bit of water＝a little water
not a little＝very非常，not a bit＝not…at all一点也不
10. throw away扔掉…→“动词＋副词”结构，e.g. throw it/them away
11. have an interview with sb＝interview sb采访某人；对某人面试；与某人面谈(p12)
①My parents have had an interview with my teacher.
②They interviewed 20 people for the job.
③There are a number of interviews with some famous football players.
12. the best model I have ever seen 我曾见过的最好的模型(p17)
the＋形容词最高级＋名词单数＋sb have/has ever done，某人曾做过的最…的…
the most wonderful film (that) he has ever watched他看过的最精彩的比赛
⑴ever通常用于疑问句中或否定句中。
e.g. ①Have/Has sb ever done sth?
②Nobody ever stepped in this cavern.没人曾经踏进过这洞穴。
⑵e ver since…自从…起到现在(用于现在完成时)，
for ever＝forever永远；永久地
13. move into the new flats→move into…搬进…，move out of…搬出… (p18)
14. lend me a book→lend sb sth＝lend sth to sb把某物借给某人，是“借出”。
〈知识链接〉borrow sth from sb向某人借某物，是“借入”。
15.a recent photo一张近期照片，write about the changes to Moonlight Town (p21)
16. a tourist attraction旅游胜地→attraction n. 吸引；向往的地方→attract vt.吸引→attractive有吸引力的
①It has become a new tourist attraction.
②Hepburn’s beauty and charm attracted Colette’s attention.
17. 常见的交通工具：bike/bicycle, bus, double-decker双层巴士, coach长途汽车, tram有轨电车, taxi, train, underground, light rail轻轨, plane, hot-air balloon热气球, aero done滑翔机
18.century＝one hundred years世纪；百年。
⑴某世纪用序数词。
如：21世纪the twenty-first century。
⑵“在某世纪”用介词in，如：in the 20th century在20世纪。
19. 1. —Eddie, have you seen my food? —Yes, I’ve just eaten it. (p6)
20. You’ve changed, Eddie. You were kind. Now you’re not. I don’t want to play with you any more.
21. You’ve changed too. You always wanted to play with me. →always＋过去式＝used to do sth
22. Coaches have been in use/service in Beijing since 1958. →have been in use＝have been used
23. I moved here with my family when I was two years old and have lived here since then. (p8)
24. Have you ever moved house? →move house搬家。
八下译林版英语第一单元笔记
八下译林版英语第一单元笔记以下是一个可能的八下译林版英语第一单元的笔记。
请注意，这是一个示例，具体内容可能因教材版本和教师教学内容而有所不同。
八下译林版英语第一单元笔记标题：开启新篇章重点词汇：1. 初学者（n.）: beginner2. 经验（n.）: experience3. 技能（n.）: skill4. 自信（adj.）: confident5. 冒险（n.）: adventure6. 成功（adj.）: successful重点短语：1. 在某方面有经验: have experience in sth.2. 增强自信: build confidence3. 开始新的冒险: embark on a new adventure4. 为...感到自豪: be proud of...5. 成功完成: successfully complete...语法重点：1. 现在进行时态（The Present Continuous Tense）的用法2. 频率副词（如always, often, seldom, never等）的用法3. 动词不定式（to do）作宾语、状语、定语时的用法日常用语：- 你需要练习你的英语口语。
You need to practice your English speaking.- 我经常在英语角和外国人交流。
I often communicate with foreigners at the English corner.- 老师鼓励我们在课堂上多发言。
The teacher encourages us to speak more in class.- 学习一门新技能真有趣！It's really fun to learn a new skill!。
八下译林英语第一单元笔记
八下译林英语第一单元笔记以下是八下译林英语第一单元的笔记，供您参考：
1. 重点单词：
vacation 假期
New York 纽约
Paris 巴黎
London 伦敦
Sydney 悉尼
Singapore 新加坡
Hong Kong 香港
stay 待在某处
the Eiffel Tower 埃菲尔铁塔
the Buckingham Palace 白金汉宫
the Sydney Opera House 悉尼歌剧院
the CN Tower 加拿大国家电视塔
2. 重点短语：
go on vacation 去度假
stay at a resort 在度假村待着
visit places of interest 参观名胜古迹
go to the beach 去海滩
do some sightseeing 观光游览
3. 重点句型：
What did you do on your vacation? 你假期做了什么？
I went to New York and visited my uncle. 我去了纽约看望叔叔。
How was your stay in Paris? 你在巴黎待得怎么样？
I had a great time staying at the Eiffel Tower. 我在埃菲尔铁塔待得很开心。
4. 重点语法：一般过去时的基本用法，表示过去发生的动作或状态。
牛津译林版八年级英语下册Unit1知识点归纳总结
1. past and present 过去和现在past 1). n. in the past(一般过去时)2). adj. in the past few years(现在完成时) 3). prep. walk past 经过=present 1). n. 现在, 目前 at present 2). n. 礼物 receive a present 收到一件礼物 2. in the bowl 在碗里; on the plate 在盘子上 3. 1).过去常常做某事(现在不做了) usedto do sth. = often did sth. in the pastused to be…= … was/were once… = was/were… in the past 和某人分享某物 share sth. with sb.Eg. You often shared food with me in the past. = Youfood with me.You used to be so kind to me. = Youto me.2). 习惯于, 适应于(做)某事 be/get used to (doing) sth. (现在仍如此做)我习惯于上午六点起床。
Iup at 6 a.m.3). 区分：used to do sth. 过去常常做某事(现在不做)get/be used to doing sth. 习惯于做某事(to 为介词)4. just 1). adv. 刚才(现在完成时) I’v e just eaten it.2). adv. 正好, 恰好(加强语气) The shirt is just my size.这件衬衫正和我的尺码。
3). just now 刚刚, 刚才(一般过去时);5. change 1). v./n. 改变, 变化 changes in/to … ……的变化 T h etown has changed a lot over the years.(v.)= There have been great changes over the years. (n.)= Great changes have taken place over the years.2). n. [U] 零钱. Here is your change. 这是你的零钱。
八下.英语书译林版u1笔记
八下.英语书译林版u1笔记英文回答：Unit 1 English in Our Time.What are the advantages of English as a global language?English is widely spoken as a native language in countries such as the United States, the United Kingdom, Canada, Australia, and New Zealand.English is an official or co-official language in many countries around the world, including India, Pakistan, Nigeria, and South Africa.English is the dominant language of business, science, and technology.English is widely used in the media, includingnewspapers, magazines, and television shows.What are the challenges of learning English as a non-native speaker?English has a complex grammar system.English has a large vocabulary.English pronunciation can be difficult for non-native speakers.English spelling can be irregular.How can we overcome the challenges of learning English as a non-native speaker?Practice regularly.Immerse yourself in the English language.Find a language partner or tutor.Use technology to your advantage.中文回答：Unit 1英语在我们时代。
牛津译林版英语八年级下册 Unit 1 语法、词汇、句型知识点总结(详细版)
牛津译林版英语八年级下册Unit 1 语法、词汇、句型知识点总结（详细版）8B Unit 1 Past and presentComic strip & Welcome to the unit1.I've just eaten it.我刚才把它吃了。
just此处用作副词，意为“刚刚，刚才”，通常与现在完成时连用。
Mr Wang has just left our classroom.王老师刚刚离开我们的教室。
I've just heard the news.我刚听到这个消息。
拓展：①just 副词，还可意为“正好，恰好；仅仅，只是”，起加强语气的作用。
This jacket is just my size.这件夹克衫正合我的尺码。
That's just what he wanted.那正是他所要的。
He is just a child.他仅仅是一个孩子。
I just want to talk to you.我只是想和你谈谈。
①just now意为“刚才，刚刚”，相当于a moment ago，常用于句末，用于一般过去时态的句子中。
I met one of my friends in the street just now.我刚才在街上遇到了我的一个朋友。
①just then 意为“就在那时”。
Just then, someone knocked at the front door.就在那时，有人敲了敲前门。
2.Why?为什么?这是一个省略问句，其完整形式是“Why did you eat my food?”。
why引导的特殊疑问句用来询间原因，通常用because（因为）引导的句子来回答。
—Why didn't you come to the meeting yesterday?你昨天为什么没来参加会议?—Because I had a bad cold.因为我患了重感冒。
八下英语译林版笔记
八下英语译林版笔记English Answer:Unit 1:Lesson 1:Vocabulary: Hobbies, interests, personality traits. Grammar: Present simple tense, verb "to be"Lesson 2:Vocabulary: Daily routines, time expressions.Grammar: Present continuous tense, time adverbs.Lesson 3:Vocabulary: School life, subjects, classrooms.Grammar: Possessive pronouns, prepositions of place.Unit 2:Lesson 4:Vocabulary: Animals, animal habitats.Grammar: Present perfect tense, past participles.Lesson 5:Vocabulary: Food, drinks, meals.Grammar: Comparatives and superlatives.Lesson 6:Vocabulary: Clothing, accessories, stores.Grammar: Modal verbs (can, could, may, might)。
Unit 3:Lesson 7:Vocabulary: Weather, seasons, climate.Grammar: Conditional sentences (Type 1)。
Lesson 8:Vocabulary: Travel, transportation.Grammar: Past simple tense, irregular verbs.Lesson 9:Vocabulary: Sports, activities, fitness.Grammar: Future simple tense, time expressions.Unit 4:Lesson 10:Vocabulary: Science, experiments, discoveries. Grammar: Passive voice.Lesson 11:Vocabulary: Technology, gadgets, social media. Grammar: Present perfect continuous tense.Lesson 12:Vocabulary: Art, music, literature.Grammar: Relative clauses.Unit 5:Lesson 13:Vocabulary: Health, nutrition, lifestyle.Grammar: Modal verbs (should, must, have to)。
译林版八下英语书笔记
译林版八下英语书笔记Unit 1: Dreams Take Flight.Lesson 1: A Dream Within a Dream.Word Bank: memoir, legacy, dedicate, elaborately, illustration.Reading Summary: Frederick Douglass's autobiography, a poignant tale of slavery and resilience, is a testament to the transformative power of literacy.Discussion Questions:What difficulties did Frederick Douglass encounter as a slave?How did literacy empower Douglass to fight for his freedom?How does Douglass's story highlight the importanceof education and perseverance?Lesson 2: Dreams Deferred.Word Bank: pledge, illuminate, vivid, poignant, reflect.Reading Summary: Langston Hughes's famous poem explores the shattered dreams and hopes of African Americans in a society marked by prejudice and discrimination.Discussion Questions:What is the central message of "Dreams Deferred"?How does Hughes use imagery and symbolism to convey the plight of his people?What are some ways we can work towards fulfilling deferred dreams?Lesson 3: A Day in History.Word Bank: pioneer, commemorate, heritage, significant, inspiring.Reading Summary: Martin Luther King Jr.'s "I Have a Dream" speech chronicles a groundbreaking moment in the American Civil Rights Movement, calling for equality and unity.Discussion Questions:What was the significance of Martin Luther King Jr.'s "I Have a Dream" speech?How did King's words inspire and galvanize theCivil Rights Movement?What lessons can we learn from King's legacy of nonviolent resistance?Lesson 4: Civil Disobedience.Word Bank: obey, dissent, ethical, moral, conscious.Reading Summary: Henry David Thoreau's essay argues that individuals have a moral obligation to disobey unjust laws, a principle that has influenced countless social movements.Discussion Questions:What are the key arguments Thoreau makes in favor of civil disobedience?When is it justified to break the law?How does Thoreau's philosophy relate to contemporary issues of social justice?Unit 2: Facing Challenges.Lesson 1: Overcoming Obstacles.Word Bank: resilience, adversity, setback, triumph,perseverance.Reading Summary: Helen Keller's autobiography recounts her life as a deaf-blind woman, demonstrating the extraordinary power of the human spirit to overcome seemingly insurmountable challenges.Discussion Questions:What were the major obstacles Helen Keller faced in her life?How did Keller overcome these obstacles and achieve success?What lessons can we learn from Keller's story about the importance of resilience and determination?Lesson 2: The Challenges of War.Word Bank: patriotism, sacrifice, veteran, conflict, courage.Reading Summary: Tim O'Brien's short story explores the psychological and emotional challenges faced by soldiers during the Vietnam War.Discussion Questions:What are the different ways war affects the lives of soldiers?How does O'Brien use imagery and symbolism to convey the complexities of war?What are some of the ethical dilemmas soldiers may face in war?Lesson 3: Environmental Challenges.Word Bank: pollution, ecosystem, biodiversity, conservation, sustainability.Reading Summary: Rachel Carson's book "Silent Spring"raised awareness about the dangers of pesticides and pollution, inspiring the modern environmental movement.Discussion Questions:What were Rachel Carson's main arguments in "Silent Spring"?How did her book influence the development of environmental regulations?What are some of the key environmental challenges we face today?Lesson 4: Health and Well-being.Word Bank: nutrition, lifestyle, exercise, mental health, well-being.Reading Summary: Various articles explore the importance of leading a healthy and balanced life, encompassing physical, mental, and emotional well-being.Discussion Questions:What are the key components of a healthy lifestyle?How can we promote physical and mental well-beingin our daily lives?What are some of the common health challenges people face today?。
牛津译林版八年级英语下册Unit1PastandPresent知识点总结
Unit 1 Past and Present一、词性转换1. possibe (反义词)2. block（复数）3. marry形容词）4. pollute（名词）5.recent（副词） ___6.north（形容词）7. communicate（名词）_________________ 8.exact（副词）_________________________9..wife（复数） ____________ 10.factory（复数）_______________________二、翻译词组1.在碗里_______________________________2.不同时代的交通工具_____________________3.和……一起玩_________________________4.在南部_________________________________5.搬到另一套公寓_______________________6.结婚___________________________________7.在这些年期间_________________________8.变化很大_______________________________9.在过去_______________________________10.在目前________________________________11.把……变成__________________________12.玩牌、下象棋___________________________13.水污染______________________________14.过去常常______________________________15.把……放进……里____________________16.采取行动______________________________17.改善形势____________________________18.在某些方面____________________________19.感到有点孤独________________________20.有时；偶尔____________________________ 21.一个现代化的小镇____________________22.和某人有个约见._______________________23新火车站____________________________24.事实上________________________________25.顺便问一下__________________________26.一生__________________________________27.步行去上学__________________________28.在小学________________________________29.等待下一个__________________________30.绝大多数家庭__________________________31.月光镇的变化________________________32.一个钢铁厂____________________________33.和以前一样频繁______________________34.在两边________________________________三、词汇运用根据汉语意思或首字母填空1. Wuxi is in the________________（北部的）part of Jiangsu.2. There were two shoe__________________（工厂）in our home town five year ago.3. The____________________（环境）of the earth is becoming worse and worse.4. The football star loves his girlfriend and he decides to get m____________ to her next month.5. One hundred years is a c______________.6. ---What’s on TV?--- Chairman Xi is having an i_________________ with President George Bush.7. I like the f__________________ fruit and they taste great.8. We should warn them not to ____________ the rivers.(污染)9. There have been many changes in Wuxi in the ___________years.(最近的)10. We shouldn’t always play jokes on those children at ______________school.(初级的)11.What a poor child! He hasn’t got a present from his parents _________since two years ago.(还)12.The doctor said they would never forget the terrible_____________(形势) after the snowstorm.13.I have been there many times in the p________________.14.I’m afraid I cant help you at p____________________.15.In a good ________________(条件), we have a happy life.B）适当形式填空1. Eddie_________________ (live) with Millie since he was born.2. There_________________ (be) great changes in Jianhu recently.3. I ____________ (make) a lot of friends since I______________(come) to this school.4. Do you have the same____________ (feel) with me?5. It's_____________ ______________(luck) for him to lose the game.7. The air in mountain areas is _____________ (good) than that in big cities.8. The little boy used to_____________ (cry) when he was a baby.9. The government took a lot of ____________ (act) to reduce the water pollution.10. Tom knows Lucy very_____________ (good).11. The twins _________just __________(visit)the museum and it’s very interesting.12. My mother_______________(prepare) for dinner when I arrived home.13. Great changes_____________(take) place in China over the past 20years.14. It ___________nearly ten years since you started to play the piano.（be）15. They did nothing and ___________(sell) their house at last.16. The hunters __________(catch) a tiger in the forest two days ago.17. Some teachers are looking after the children while others ____________(give) out clean water.18. Where is Jim? He ____________(go) to the library already.19. Mr Green _____________(not come) back to China yet.20. I __________ ( not see) you for a long time.21.John _____________(be) to Beijing three times.22. We ___________ never ____________ ( not eat) so delicious food.23. Mary always ____________ (get) up too late, and never had enough time forbreakfast.24. I _______________ (not hear) from him since he lived in Shanghai.25. He ________________ (be) to Hangzhou three times.26. Mary is not here. She __________________ (go) to Tai Pei.27. He’ll write to me as soon as he _____________ (reach) Xian.28. ----____________ you ___________ (see)the film?---Yes, I __________________ (see) it two weeks ago.29. Tom! ________________ (not do) it like that next time.30. The teacher _________________ (talk) to my father when I got home.31. Thirty bikes_________________ (mend) by Uncle Wang last week.32. We can use computers ______________(send) messages.33. Look at the dark clouds . It _______________ (rain) soon.34. We’ll go to visit the Great Wall, if it ______ (not rain) tomorrow.35. Listen! Who ______ (sing) an English song in the room?36. Li Ping ______ ( do) his homework at six yesterday evening.37. ______ you ________( have) your lunch yet?39. I want to buy some presents for all my family, but I ______(not choose) any yet.40. Tom _______ (watch) TV while his father was reading.41. China _________ (change) a lot since 1978.42. The machine ______ (make) in China in 2002.四、句型转换1. She used to live in the city.（改为否定句）She _______ _______to live in the city.2. I have learned a lot about Beijing's past and present.（改为一般疑问句）_______ you _______a lot about Beijing's past and present?3. They have moved to other areas in Beijing, and I feel a bit lonely at times.（同义句转换）They have moved to other areas in Beijing, and I feel a bit lonely _______ _______ _______ _______.4. It has become a new tourist attraction in Sunshine Town.（完成反意疑问句）It has become a new tourist attraction in Sunshine Town,_______ _______?5. They have known each other for about twenty years.（对画线部分提问）_______ _______have t hey known each other?6. I saw the film 2046 just now.(用just做状语)I ____________ just______________ the film 2046.7. She’s already done her homework.(改为否定句)She__________ ___________ her homework ___________.8. I’ve known him since he came here.(对划线部分提问)__________ __________ ___________ you known him?9. Mary married Simon in 1999. (同义句转换）Mary and Simon ______________ ___________ in 1999.10. They moved to France because Mr. King found work there. (对划线部分提问)____________ ____________ they ____________ to France?11. They did some exercise before breakfast. (同义句)They did some exercise ____ ______ ______ breakfast.12. Sometimes I feel lonely . (同义句)I feel lonely _________ __________ __________ __________.13. He married her in 1993. (同义句)They __________ ___________ in 1993.14. It is eas y that he can see them as often as before. （同义句转换）It _________ ___________ __________ him __________ _________ them as often as before.15. I have already heard from my sister.（改为否定句）I __________ _________ from my sister ____________.16. Tom and his brother have learned English for ten years.( 对画线部分提问)____________ _____________ _____________ English for ten years?五、翻译句子1．Millie半小时前在教室。
八下英语译林版笔记 小红书
八下英语译林版笔记小红书Unit 1 Healthy eating and drinkingPart 1 Word study1. manner n. 方式Eating in a polite manner is important in some cultures.2. recommend v. 推荐Doctors often recommend eating fruits and vegetables fora healthy diet.3. contain v. 包含This drink contains a lot of sugar, so it's not good for your health.Part 2 Grammar1. The simple present tenseThe simple present tense is used to express habits, general facts, and routines.Examples:- We usually have breakfast at 7 o'clock.- The sun rises in the east.2. Adverbs of frequencyAdverbs of frequency tell us how often something happens. Examples:- Mary always walks to school.- They rarely go to the cinema.Part 3 Reading1. Reading comprehension: Healthy eatingGood nutrition is important for a healthy lifestyle. Eating a balanced diet and exercising regularly can help prevent many diseases. Here are some tips for healthy eating:- Eat a variety of foods from different food groups. This ensures that you get all the necessary nutrients your body needs.- Reduce the intake of sugary and fatty foods. Instead, opt for fruits, vegetables, whole grains, and lean proteins.- Drink plenty of water to stay hydrated throughout the day.- Limit the consumption of processed foods, as they often contain high levels of salt, sugar, and unhealthy fats.Remember, healthy eating is a lifelong commitment that can benefit both your physical and mental well-being.Part 4 Writing1. Write a paragraph about your eating habitsI have always tried to maintain a healthy eating habit. I start my day with a nutritious breakfast, usually consisting of whole grain cereal, fruits, and a glass of milk. For lunch and dinner, I make sure to include a variety of vegetables, lean proteins, and carbohydrates. I also snack on freshfruits and nuts throughout the day to keep myself energized. Occasionally, I treat myself to some sweets or junk food, but I try to limit their consumption. Overall, I believe that a balanced diet is essential for a healthy lifestyle.2. Write a paragraph about the importance of drinking waterDrinking an adequate amount of water is crucial for our overall health. Water helps to transport nutrients to our cells, regulate body temperature, and flush out toxins. It is recommended to drink at least 8 glasses of water per day, or more if you engage in physical activities or live in a hot climate. Proper hydration keeps us energized, improves digestion, and enhances brain function. Therefore, it isessential to prioritize drinking water and make it a part of our daily routine.I hope this document provides you with helpful information on healthy eating and drinking. Remember, taking care of our body is key to a happy and fulfilling life.。
牛津译林版八下Unit1知识点梳理
Unit 1 Past and prese nt1.1 Comic strip & Welcome to the unit1: past and present(1)pastn.过去，以前；in the past在过去adj.过去的，以前的；in the past few years在过去的几年里prep.经过walk past the post office 走过邮局In the past there was no un dergro und in Nanj ing.Let ' s not make t past mistakes.When I walk past the post office, I see a bird flying over the tree.(2)presentadj.现在的；目前的；出席的n.现在; 礼物; at present 现在 ; a present for you=a gift for you给你的礼物vt.介绍；出现；提出；赠送；Every one can be present ed a present at present2：You' vechanged, Eddie. You used to share food with m你变了。
你以前跟我分享食物的。
(1)change vt./vi. 改变，变更; change into变成n.变化，改变；change(s) to ..的变化Great changes to Nanj ing have take n place.(2)use n.用途；使用能力；运用头脑(或身体)的能力；vt.用，使用；行使，①used to (do sth.) 过去常常(做某事)”批注：否定形式：didn ' use to / usedn' t to② get/be used to(doing sth.)习惯于(做某事)He used to go fishing every Saturday. But since he changed his job, he barely（几乎's 不）had a chanee. He thinks he ' lb eiuserd to this busy lifestyle.useful adj.有用的；useless adj.无用的3: I first lived in the northern part of the town with my parents.Beijing is in the northern part of China.批注：注意in the north与in the northern part of的同义句转换。