
The activity topic of this section is "report an ongoing event", and the structure is the passive voice of present continuous tense. Rare wild animals are suffering from large-scale poaching, and species are on the brink of danger. Rescue operations are underway. "Being" and "suffering" are the meanings of the present progressive passive voice.The usage of present progressive passive voice is of great importance in writing a good discourse and appreciating some difficult language items, so it is vital to master it and use it flexibly in a context.1. Motivate Ss to deepen the understanding of the usage of present progressive passive voice in a fixed context.2. Enable Ss to master the usage of present progressive passive voice and use it flexibly in a context.3. Lead Ss to construct sentences or appreciate sentences used master it and use it flexibly in a context.1. Help students to appreciate the function of the usage of present progressive passive voice in a sentence2. Instruct students to write essays using the proper usage of present progressive passive voice.Look at the picture and tell me what are workers doing? What is the house being done?

The listening and speaking part aims at how to protect and help endangered animals by listening, speaking and talking about the facts and reasons. This lesson analyzes the decreasing clause of Tibetan antelope population and the measures of protecting Tibetan antelopes. So students can be guided to learn to analyse the title and use different reading skills or strategies, like scanning, skimming and careful reading.1. Read quickly to get the main ideas and the purpose of going to Tibetan; read carefully to understand what the author see and think.2. Understand the sentences of the present continuous passive voice such as “Much is being done to protect wildlife.” and the inverted sentence “Only when we learn to exist in harmony with nature can we stop being a threat to wildlife and to our planet.”3. Enhance the awareness of protecting wildlife.4. Cultivate the reading methods according to different materials.1. Read quickly to get the main ideas and the purpose of going to Tibetan; read carefully to understand what the author see and think.2. Understand the sentences of the present continuous passive voice such as “Much is being done to protect wildlife.” and the inverted sentence “Only when we learn to exist in harmony with nature can we stop being a threat to wildlife and to our planet.”3. Cultivate the reading methods according to different materials.Step 1 Leading-inWatch a video about elephants and whales and then ask:Why are they endangered ? They are killed/hunted

This lesson is about wildlife protection. The listening and speaking is about “How to protect endangered wildlife ?” Faced with the facts and numbers of wildlife loss, people begin to detect the reasons, then people such as the celebrities (Prince William and Yao Ming) are calling on to protect them. So students are guided to enhance the awareness of protecting wildlife and try to take part in some volunteer activities of protecting wildlife.1. Predict the content by using visuals. 2. Learn to use the sentences such as “I’m concerned about.... But now they are in danger. I want to know the reasons/why./ What can we do to protect them ?3. Learn from the stars like Prince William and Yao Ming and enhance the awareness of protecting wildlife.4. Guide students to try to put forward the solutions to the problems of wildlife protection and then discuss them with partners and present the results of discussion.5. Master the pronunciation of stressed syllables.1. Learn from the stars like Prince William and Yao Ming and enhance the awareness of protecting wildlife.2. Guide students to try to put forward the solutions to the problems of wildlife protection and then discuss them with partners and present the results of discussion.3. Learn to use the sentences such as “I’m concerned about.... But now they are in danger. I want to know the reasons/why./ What can we do to protect them ?4. Master the pronunciation of stressed syllables.Part A Listening and Speaking--- How to save endangered wildlifeStep 1 Lead in1. Point at the pictures on P14 and ask Q1: What message do these posters share?

The theme of this unit is human and nature, focusing on the theme of wildlife protection. Nature is a complex ecosystem, in which there are delicate balance between animals and plants. Because of the role of the food chain, the extinction of one species will produce influence, causing a series of chain reaction. Large scale extinction of species will have a serious and even irreversible impact on the ecosystem, resulting in immeasurable losses. Therefore, it is of great significance to protect wild species. To protect wild species is to protect human beings themselves. The motto of this unit is "when the buying stops, the killing can too,” which is a public service advertising slogan to protect wildlife. It tells people that every rhinoceros horn, every fur, every bowl of shark fin soup, every Ivory product, and every tiger bone product, etc. consumed by human beings, are innocent wild animals slaughtered behind them. The mission of wild aid is to ban illegal trade in endangered wildlife and mitigate climate change. It aims to educate the public to reduce the consumption demand for endangered wildlife products through public publicity and improve the awareness of environmental protection.1. Improve the awareness of wildlife protection by acquiring the knowledge of wildlife protection.2. Focus on environmental protection and protection of all lives.3. Analysis of the living environment of wild animals with appropriate thinking mode.4. Skillfully use the vocabulary and grammar knowledge of this unit to cultivate self-study ability according to the unit content5. Develop cooperative learning ability through discussion and other ways1. Enable the Ss to talk about the current situation of wild animals.2. Guide the Ss to summarize the main idea of each paragraph as well as the main idea of the text.

Step 5 Practice一、完成下列句子。1. Judy and I _______________(把車停下來(park))in an underground car Park near Trafalgar Square, where we could ______________________(讓我們的車充電(charge)).2. When we finally reached the service desk to ask for audio guides, we heard it ___________ that there were no audio guides____________(留下,剩下).3. We__________________________(發(fā)現(xiàn)自己對...很驚訝)the large number of visitors and the amount of noise at the entrance of the National Gallery.4. Judy ____________________(眼神專注于) Van Gogh’s Sunflowers. It was hard to approach the painting as there were so many people around.5. She ____________________(把這幅畫的復制品裝箱(box)) to ensure that it was delivered safely.答案:1.had our car parked get our car battery charged 2. announced left 3. found ourselves very surprised 4. had her eyes fixed on 5. had a copy of the painting boxed二、用過去分詞對下列句子進行改寫。1. Loch Ness was surrounded by beautiful natural landscape, which made it look amazing.2. Carl and his friend stayed with a generous family who offered them bread with butter and honey that was homemade.3. The family’s ancestors once attended to soldiers who were wounded in the First World War.4. The young people were attracted by the legend of Loch Ness. They watched over the lake with their cameras and binoculars, which were positioned on the hill.答案:1. Loch Ness surrounded by beautiful natural landscape looks amazing.2. Carl and his friends stayed with a generous family who offered them homemade bread with butter and honey.3. The family’s ancestors once attended to wounded soldiers in the First World War.4. The young people attracted by the legend of Loch Ness watched over the lake with their cameras and binoculars positioned on the hill.

This unit is about history and traditions. From the opening page, we can know that this unit will introduce the history and traditions around the world. As Marcus Garvey says “A people without the knowledge of their past history, origin and culture is like a tree without roots”, it is important for students to realize the importance and value of knowing the history and traditions and their further meanings. And this part ( listening and speaking ) is divided into two parts: Part A---share views on historic sites, Part B ---talk about a visit to a historic tourist destination. By talking with a foreigner, the speakers introduce the historic attractions and their cultures. Part A is that William, a British student, who was going to visit the Confucius Temple and a Chinese student, Xiao Kong, who was going to the Confucius Temple to meet with the members of the research group, went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. Part B is a conversation between Xiao Yan, a youth hostel receptionist and Paul, a backpacker about the feelings and experience after visiting the Chinese famous tourist attraction Pingyao.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to talk about historic spots and great person.3. Instruct students to use functional sentences of showing one’s excitement, surprise and disappointment.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to discuss with their peers the related topics.3. Enable students to use the functional items of showing one’s excitement, surprise and disappointment.

This teaching period mainly deals with grammar: The past participle is used as attributive and objective complement.1. Guide students to review the basic usages of the past participle used as attributive and objective complement.2. Lead students to learn to use some special cases concerning the past participle used as attributive and objective complement flexibly.3. Strengthen students’ great interest in grammar learning.1. Help students to appreciate the function of the past participle used as attributive and objective complement.2. Instruct students to write essays using the past participle used as attributive and objective complement.Step1:溫故而知新。Analyze the underlined phrases and then sum up the common usages of the past participles.1.(教材P41)They had castles built(build) all around England, and made changes to the legal system.2.(教材P42)They use the same flag, known(know) as the Union Jack,...3.(教材P42)Judy and I had our car parked(park) in an underground car park near Trafalgar Square, where we could get our car battery charged(charge).Common points: f the past participle used as attributive and objective complement.Step 2:過去分詞作定語時的意義1.及物動詞的過去分詞作定語,在語態(tài)上表示被動;在時間上,常表示動作已經(jīng)發(fā)生或完成,有時也不表示時間性。Our teacher watched us doing the experiment and gave us a satisfied smile at last.我們的老師看著我們做實驗,最后給了我們一個滿意的微笑。The plan put forward at the meeting will be carried out soon.會上提出的計劃將很快被執(zhí)行。2.不及物動詞的過去分詞作定語,它不表示被動意義,只強調(diào)動作完成。Many little kids like gathering fallen leaves in the yard.

Listening and Speaking introduces the topic of “Take part in a youth project”. The listening text is an interview about "sharing views on historical sites". Through listening to a dialogue between Chinese and foreign students on the way to the Confucius Temple, students can understand their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts, so as to realize and think about the profound influence of Confucius and his thoughts on Chinese historical tradition. At the same time, the dialogue naturally integrates English idioms and mentions Shakespeare, the British playwright, so as to provide language materials and context for students to understand English idioms and related cultural allusions, as well as to compare Chinese and foreign cultures, which is helpful for students to understand and express the language such as history, tradition, culture and custom significant impact.Text analysis: listening text is a dialogue between a British student and a Chinese student when he goes to the Confucius Temple. When William, a British student, visited the Confucius Temple, he asked Xiao Kong, a Chinese student, for directions. Xiao Kong was just going to the Confucius Temple to meet with the members of the research group, so they went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. From the perspective of foreign tourists, this paper describes their thoughts on Confucius, the great son of Confucius, who had a profound impact on Chinese history and cultural tradition, and his education.Listening and Talking introduces a visit to a historic tourist destination. Tourism is a common way to understand a country's history, culture, and customs and so on. Students listen to the dialogue between Xiao Yan, a youth hostel Usher, and Paul, a backpacker, to learn about Pingyao's famous historical and cultural attractions and Paul's travel experience and experience as a foreign tourist.

Features of languages1.Finally, in the 20th century, the southern part of Ireland broke away from the UK, which resulted in the full name we have today: the United Kingdom of Great Britain and Northern Ireland.該句是一個復合句。該句主句為:the southern part of Ireland broke away from the UK;which resulted in the full name we have today為which引導的定語從句代指前面整句話的內(nèi)容,we have today為定語從句修飾先行詞name。譯文:最后,在20世紀,愛爾蘭南部脫離英國,這導致了我們今天有的英國的全名:大不列顛及北愛爾蘭聯(lián)合王國。2.Almost everywhere you go in the UK, you will be surrounded by evidence of four different groups of people who took over at different times throughout history.該句是一個復合句。該句主句為:you will be surrounded by evidence of four different groups of people;其中Almost everywhere you go in the UK為讓步狀語從句; who took over at different times throughout history為定語從句修飾先行詞people。譯文:幾乎無論你走到英國的任何地方,你都會發(fā)現(xiàn)歷史上有四種不同的人在不同的時期統(tǒng)治過英國。3.The capital city London is a great place to start, as it is an ancient port city that has a history dating all the way back to Roman times.該句是一個復合句。該句主句為:The capital city London is a great place to start; as it is an ancient port city that has a history dating all the way back to Roman times.為原因狀語從句;dating all the way back to Roman times為現(xiàn)在分詞短語作定語修飾history。

Step 1 Lead inThere are many interest of places in the UK. What do you know ?The Big Ben the London Tower the Thames RiverStep 2 Before reading---analyze the titleBeautiful Ireland and its traditionWe know that the article mainly tells about the beauty and traditions of Ireland. Step 3 While reading---Task 1Read the text and answer the following questions.Q1: What makes the Irish countryside exciting and inspiring?Its beauty and how it offers something for all the scenes.Q2: What are the best ways to experience some Irish traditions and cultures?By stopping by a village pub and relaxing with a drink and traditional meal while listening to music and watching dancingQ3: What is the meaning of “breathe in the sweet scent of fresh flowers while birds greet the new day with their morning song ?”It means to not just smell but also breathe in the smell of fresh flowers early in the morning as the birds sing their first song of the new day.Q4: What are the best ways to experience Chinese traditions and customs ?By travelling to different places and using all your senses to experience everything and by interacting with local people.Step 4 While reading---Task 2Analyze the descriptive paragraph1. Identify and underline the paragraph’s introductory sentence and the ending sentence.Introductory sentence: Ireland’s beautiful countryside has always had a great influence on its people and traditions.Ending sentence: And if you introduce yourself to a friendly face, you are more than likely to experience local culture and customs first-hand.2. The paragraph talks about different senses in different places. Write the senses and places in the order that they appear.

4. When he got absorbed in his world of music, he felt as if he could “see” the beauty of the world around him, like he had in his previous life.P·P as adverbial: _________________________________________________________________.Function: _______________________________________________________________________.Step 5 Solid Complete the passage with the words in brackets in their correct forms.Well known as a successful band, the Impact members show quite a few striking qualities. They never ever give up. When _____________(question) by the media, they are not _____________(discourage) and practise even harder. They are improving themselves by attending several master training class. They are united. _____________(fill with) team spirit, they act as a whole, always aiming for glory. Step 6 Difference and similarity from -ingObserve the following examples.1. He went out, shutting the door behind him.=He went out, ________________________________________________________.2. Not knowing what to do, he went to his parents for help.=__________________________________________, he went to his parents for help.Similarity: _______________________________________________________________________________________________________________________________________________________.Difference : _______________________________________________________________________________________________________________________________________________________.Step Practice1. ________ in a hurry, this article was not so good. 因為寫得匆忙, 這篇文章不是很好。2. ________ carefully, he found something he hadn’t known before. 他仔細讀書時, 發(fā)現(xiàn)了一些從前不知道的東西。3. ________ why he did it, the monitor said it was his duty. 當被問及他為什么要這么做時, 班長說這是他的職責

Step1:自主探究。1.(教材P52)Born(bear) in the USA on 2 January 1970, Whitacre began studying music at the University of Nevada in 1988.2.(教材P52) Moved(move) by this music, he said, “It was like seeing color for the first time.”3.(教材P56)I was very afraid and I felt so alone and discouraged(discourage).4.(教材P58)Encouraged(encourage) by this first performance and the positive reaction of the audience, I have continued to play the piano and enjoy it more every day.Step2:語法要點精析。用法1:過去分詞作表語1).過去分詞可放在連系動詞be, get, feel, remain, seem, look, become等之后作表語,表示主語所處的狀態(tài)Tom was astonished to see a snake moving across the floor.湯姆很驚訝地看到一條蛇正爬過地板。Finally the baby felt tired of playing with those toys.終于嬰兒厭倦了玩那些玩具。注意:1).過去分詞作表語時與被動語態(tài)的區(qū)別過去分詞作表語時,強調(diào)主語所處的狀態(tài);而動詞的被動語態(tài)表示主語是動作的承受者,強調(diào)動作。The library is now closed.(狀態(tài))圖書館現(xiàn)在關閉了。The cup was broken by my little sister yesterday.(動作)昨天我妹妹把杯子打碎了。2)感覺類及物動詞的現(xiàn)在分詞與過去分詞作表語的區(qū)別過去分詞作表語多表示人自身的感受或事物自身的狀態(tài),常譯作“感到……的”;現(xiàn)在分詞多表示事物具有的特性,常譯作“令人……的”。

1. Get basic information about Eric; read deeply to understand the history and development of the virtual choir.2. Understand what the function of the virtual choir is and how to make a virtual choir.3. Understand the meaning of some languages in the context of the text through question guidance, such as “Many people do not have close friends or contacts who have the same interest in music.” and so on.Step 1 Leading-in1. Answer the following questions.Q1:Do you know the Apps like Tik Tok and Quick Hand?Q2: Do you want to make a Tik Tok video or a Quick Hand video?2. Play a Tik Tok video Step 2: Understanding the title Q1:What does the title mean ?Q2: Is the article a narration or exposition? Why? Q3: Can you change the title ? If you can, what is the title?Step 3: Scanning the whole text and getting the basic information1. Answer the following questions.Q1:Who came up with the idea for a virtual choir?Q2: Where did Eric studied the musical composition?Q3: What is his song?2. Find the main idea of each paragraph3. Deal with some new words.Step 4: Reading carefully to get detailed informationPara 1 How to make a virtual choir1. PreparationA. tools: a virtual camera; an Internet connectionB. hero/heroin: friends or some individuals who have the same interests2. Process

This section focuses on "learning about experiencing music Online". This virtual choir is a new form of music performance. Members from all over the world don't need to love to come to a place. Instead, they use the new technology to model the various parts and wonderful virtual harmony group of music in the family. Students need to understand the main meaning of each paragraph. Finding topic sentences is an important way to understand the general idea of a paragraph. After the topic sentence, it is usually the detail sentence that supports and explains the topic sentence. Some paragraphs have obvious subject sentences, for example, the first sentence of the second paragraph is the subject sentence of the paragraph, and the following sentenceStudents need to pay attention to the topic sentences and key sentences, and then pay attention to how the sentences after the meaning explain, explain and support the topic sentences or key sentences before.1.Guide students to learn about experiencing music online2.Guide students to scan and circle the information in the text.3.Guide students to find the numbers and dates to fill in the timeline.4.Guide students to learn more about music by completing the sentences with the correct forms of the words and phrases. And then make a mind map about the outline of the passage.1. Guide students to pay attention to reading strategies, such as prediction, self-questioning and scanning.2. Help students sort out the main meaning of each paragraph and understand the narrative characteristics of "timeline” in illustrative style.3. Lead students to understand the changes that have been caused by the Internet.

The Internet celebrity Gao Yifeng. Years ago, he owned 5 companies and the staffs over 1,000, but during the economy crisis, he became nothing but debt. He was so worried that his hair became white overnight. There was a time when he wanted to killed himself. But after listening to the song Start Over by Liu Huan, he decided to cheer himself up. He started a steamed bun shop and gradually became a national chain shops. Now he became successful again.Walter Haddon said, “Music is the medicine of a troubled mind.” Music contains such a pleasant and inspiring force. Music gave him courage and bravery. When he listened to the song, it made his spirit fly like a kite in the wind. Music gave him strength and brought him relief. It was the rock I leant on to become strong and to get through those hard times. I hope none of us have to go through the same kind of suffering that he did. At the same time, we all go through various periods when we feel sad or alone. During those times, music can help us in the same way that it helped him. I hope we all will somehow begin to treasure music and make it a part of our life. Thank you for your listening !5.Revise your writing each other.Does he/she explain how music has changed his/her/someone else’s life?Are some of the rhetorical devices included and used properly ?Does he/she talk about how music makes him/her/someone feel?Is the first word in each sentences capitalised?Does he/she use correct punctuation ?

科學家預測,就地區(qū)而言,位于低緯度的大部分國家,農(nóng)作物的產(chǎn)量將減少;而位于高緯度的國家,農(nóng)作物產(chǎn)量有可能增加。由于不少發(fā)展中國家位于低緯度地區(qū),因此,氣候變化的這種區(qū)域差異性,可能會使發(fā)展中國家所面臨的問題更為嚴峻。板書:3全球變暖將加劇水資源的不穩(wěn)定性與供需矛盾。介紹:全球變暖會影響整個水循環(huán)過程,可能使蒸發(fā)加大,改變區(qū)域降水量和降水分布格局,增加降水極端異常事件的發(fā)生,導致洪澇、干旱災害的頻次和強度增加,以及地表徑流發(fā)生變化。隨著徑流減少,蒸發(fā)增強,全球變暖將加劇水資源的不穩(wěn)定性與供需矛盾。轉折:既然全球變暖會引起很多不利影響,那么作為人類應如何面對這一挑戰(zhàn)呢?這就是我們要討論的第三個問題。板書:三、氣候變化的適應對策討論:請大家閱讀結合教材P53氣候變化的適應對策部分討論人類應如何面對全球變暖這一問題 呢?

1.改善城市環(huán)境:治理河流、控制大氣污染物、大力加強綠化建設為改善城市環(huán)境,上海市全面展開對大氣、河流、噪聲等多方面的治理工作。如蘇州河的治理、降低城市污染物濃度、加強綠化建設,截止1990年,市區(qū)綠化覆蓋率達到20.3%。2.改善城市交通、改善居住條件擴寬主干道,修建環(huán)城公路,修筑了南浦大橋和揚浦大橋,新修城市高架公路和地鐵,改造住宅。3.控制城市規(guī)模建立衛(wèi)星城,開發(fā)新區(qū),有效地控制城市中心區(qū)的規(guī)模。思考:什么時候許多國家采取措施保護和改善城市環(huán)境?你認為可以采取哪些措施來保護和改善城市環(huán)境?上海市保護和改善城市環(huán)境的措施:上海的衛(wèi)星城有哪些?上海新建了哪個新區(qū)?目前浦東新區(qū)在上海的地位如何?建立衛(wèi)星城和開發(fā)新區(qū)可以起到什么作用?上海市為改善交通條件,做了哪些工作?

過渡:在實際生活中,城市內(nèi)部空間結構并非完全按照這一經(jīng)濟規(guī)律呈現(xiàn),而是更具復雜性。這說明除了經(jīng)濟因素外,還有很多其他因素在起作用,請大家結合你的認識、圖2.9和案例1:紐約市的少數(shù)民族區(qū)談談你的看法。(2)其他因素I收入——形成不同級別住宅區(qū)的常見原因。有能力支付昂貴租金和選擇最佳居住環(huán)境的人,其居住地往往形成高級住宅區(qū)。II知名度——城市內(nèi)某些地區(qū)在歷史、文化或經(jīng)濟方面具有很高的聲譽,這往往會吸引更多新的住宅或商場建在該處,以提高其知名度。III種族聚居區(qū)的形成——在有些城市的某一區(qū)域內(nèi),如果某個種族或宗教團體占優(yōu)勢,就可能形成種族聚居區(qū)。如紐約市的唐人街、哈林區(qū)、小意大利區(qū)等。IV歷史因素——城市的建筑物和街道設計可以維持久遠,早期的土地利用方式對日后的功能分區(qū)有著深遠的影響。

1.生產(chǎn)上的聯(lián)系:有投入——產(chǎn)出的關系工業(yè)生產(chǎn)的過程復雜,工序繁多,往往需要經(jīng)過多家工廠的加工才能完成一種產(chǎn)品的生產(chǎn)過程。因此,在這些工廠之間就存在著產(chǎn)品與原料的聯(lián)系。一家工廠生產(chǎn)的產(chǎn)品是另一家工廠的原料,這兩家工廠之間就形成了工序上的工業(yè)聯(lián)系。2.非生產(chǎn)上的聯(lián)系:如地理空間上的聯(lián)系布局在同一個工業(yè)區(qū)內(nèi),共同利用工業(yè)區(qū)的道路、供水、供電、通信等基礎設施以及其他生產(chǎn)、生活服務設施,或者共同利用當?shù)亓畠r的勞動力,形成了空間利用上的工業(yè)聯(lián)系。我國許多地方的經(jīng)濟技術開發(fā)區(qū)就是建立在這種工業(yè)聯(lián)系基礎上的。(二)工業(yè)集聚1.形成具有工業(yè)聯(lián)系的一些工廠往往近距離地聚集起來,形成工業(yè)集聚現(xiàn)象。2.工業(yè)集聚可獲得效應(1)工業(yè)集聚可以加強企業(yè)間的信息交流和技術協(xié)作,降低中間產(chǎn)品的運輸費用和能源消耗,進而降低生產(chǎn)成本,提高生產(chǎn)效率和利潤,取得規(guī)模效益。

一般情況下,凡是支持物對物體的支持力,都是支持物因發(fā)生形變而對物體產(chǎn)生彈力。所以支持力的方向總是垂直于支持面而指向被支持的物體。例1:放在水平桌面上的書書由于重力的作用而壓迫桌面,使書和桌面同時發(fā)生微小形變,要恢復原狀,對桌面產(chǎn)生垂直于桌面向下的彈力f1,這就是書對桌面的壓力;桌面由于發(fā)生微小的形變,對書產(chǎn)生垂直于書面向上的彈力f2,這就是桌面對書的支持力。學生分析:靜止地放在傾斜木板上的書,書對木板的壓力和木板對書的支持力。并畫出力的示意圖。結論:壓力、支持力都是彈力。壓力的方向總是垂直于支持面而指向被壓的物體,支持力的方向總是垂直于支持面而指向被支持的物體。引導學生分析靜止時,懸繩對重物的拉力及方向。引導得出:懸掛物由于重力的作用而拉緊懸繩,使重物、懸繩同時發(fā)生微小的形變。重物由于發(fā)生微小的形變,對懸繩產(chǎn)生豎直向下的彈力f1,這是物對繩的拉力;懸繩由于發(fā)生微小形變,對物產(chǎn)生豎直向上的彈力f2,這就是繩對物體的拉力。
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