Unit 6 课时2 Understanding ideas（Grammar）（分层作业）英语外研版2024七年级上册

Unit 6 Fantastic friends 第2课时：Understanding ideas(Grammar) 分层作业 核心知识速记 03拓展培优 01基础达标 04思维进阶 02能力提升 词汇 1 beaver /ˈbiːvə/ n. 河狸,海狸 3 engineer /ˌendʒəˈnɪə/ n. 工程师;设计师 2 wolf /wʊlf/ n. 狼 句型 1. 我们在学校为“爱鸟周”活动学习鸟类知识。We're studying birds for Bird Week at school. 2. 我现在正在公园里看鸽子I'm watching pigeons in the park now. 3. 那只鸽子正在水里看自己呢！That pigeon is looking at itself in the water! 4. 看！这只兔子能跳一米高！Look! The rabbit is jumping one metre high! 5. —那匹马在睡觉。—我简直不敢相信。它还站着呢。它能那样睡吗？ —The horse is sleeping. —I can’t believe it. It is standing . Can it sleep like that? 6. 我在看树上的猫。I am watching the cat in the tree. 7. 但它有什么用呢？But what’s it for? 8. 这个池塘会保护他们免受狼、熊等动物的侵害。The pool will protect them from wolves, bears, etc. 1、 单词默写。 1.n. 河狸,海狸 　　　　　  2.n. 狼 　　　　　  3.n. 工程师;设计师 　　　　　  二、词组默写。 1. __________________look like 2 .__________________ protect ... from .... 3.__________________such nice work 4 . __________________nature’s engineers 5. __________________by the river 三、根据要求完成句子 1.但它有什么用呢？But __________ it ________? 2.池塘将保护他们免受狼和狐狸的危害。 The pond will _________ them _________ wolves , foxes,etc. 3. 多么好的杰作啊。It’s _________ _________ _________ . 4.另一只正在试图找到食物。The other one ________ _________to find food. 5.海狸真的是“大自然的工程师”！Beavers are really “ _________ _________”！ 四 、用括号内所给词的适当形式填空。 1．Now two beavers (swim) in the pond over there. 2．We don’t like (wolf), because they are scary. 3．Please tell me the (engineer) names. I need to make sure they are all here for the meeting. 4．It’s very important for us ( protect) the environment. 5．Many visitors come to Tibet every year because of its (nature) environment. 6．Our parents protect us from (get) hurt. 7．You should go outdoors to have a walk in (such ) fine weather. 8．Look, the girl (fly) a kite. Let’s go and play with her. 9．The basketball matches between the teams from the villages are very exciting. Many people (watch) them. 10．We usually stay in when it snows, but now we (build) a snowman outside. 5、 短文填空 Earlier this year, a family of beavers caught the world’s attention. In just two days, they built a dam (坝) that the Czech government had planned for seven years but never started. Their work saved 1.2 million dollars. People worldwide 1 (impress) by these hard-working animals. But if you know anything about beavers, you may not find the news 2 (surprise). Beavers are like natural engineers. Using strong teeth, beavers cut branches to build dams and homes. They also add grass, rocks, and mud 3 (make) them stronger. Even young beavers help! But why do they build dams? Experts say it’s for safety. On land, beavers move slowly and they’re very likely to be in danger. In the water, they are great 4 (swim) and can hold their breath for 15 minutes. Their dams create ponds that protect them from other animals like bears. Beavers remind us that every creature 5 (play) an important role in nature. By working with these furry engineers, we can protect our environment better. 6、 阅读理解。 Many people say dolphins are intelligent. They can learn, think, and understand things quickly. Scientists say sometimes dolphins show they are really smart, just like humans (人类). How? Talk Like humans, every dolphin has its “name”. The name is a special whistle (口哨). Every dolphin chooses a whistle as (作为) its name, usually by its first birthday. Dolphins like to “talk” to each other about a lot of things-such as their age, their feelings, and danger around. Understanding dolphin’s talk is not easy for humans. No one can "speak dolphin"yet, but some scientists are trying to learn. Play Dolphins live in groups and they often join other dolphins from different groups to play games and have fun-just like people. Sometimes they run after other dolphins carrying things and throw these things back and forth. Scientists believe playing together is something only intelligent animals do. Teamwork Dolphins and humans are similar (相似的) in another way: They both make plans for getting things they want. In the seas of southern Brazil, for example, dolphins use an intelligent way to get food. When there are fish near a boat, dolphins will signal (示意) to fishermen. With the dolphins’ help, fishermen can catch a lot of fish. In return (回报), dolphins can get some to eat. 1．The underlined word “intelligent” in Paragraph 1 is closest to the meaning of ________. A．funny B．difficult C．smart D．dangerous 2．How does a dolphin get a name? A．By choosing a whistle for itself. B．By talking with each other. C．By having its first birthday. D．By trying to “speak dolphin”. 3．Which of the following can not show dolphins are smart? A．Dolphins “talk” with each other. B．Dolphins live in groups. C．Dolphins help fishermen to get food. D．Dolphins play games with each other. 4．Choose the best title for this passage. A．The Incredible Dolphin B．Dolphins’ Talk C．Intelligent Animals D．Humans’ Friend 7、 完形填空。 Animals are our best friends. They are important to us. They 1 together with us on the Earth. We cannot live without animals. So we should take good care of them. Then how can we protect  animals? First ,we should 2 the importance of protecting wild animals. Animals are an important source (来源) of food. Every animal has its place in the balance (平衡) of 3 . If we destroy (破坏) a kind of animal, we will have many other 4 very soon. For example, when farmers 5   a large number of hawks (鹰), the mice will destroy farmers rice. Why? Because hawks eat 6 . Without hawks. the mice will become 7 . Second, let people know how to protect animals - 8 killing wild animals and protect their 9 . If we see other people destroy animals homes, we should stop them. 10 wild animals is the duty of each of us. Let s protect animals together！ 1．A．work B．study C．live D．play 2．A．understand B．complete C．forget D．win 3．A．time B．nature C．history D．weather 4．A．ideas B．dreams C．grammars D．problems 5．A．save B．buy C．kill D．feed 6．A．mice B．rice C．grass D．leaves 7．A．more and more B．less and less C．higher and higher D．smaller and smaller 8．A．enjoy B．stop C．keep D．practise 9．A．friends B．food C．babies D．homes 10．A．Sharing B．Cleaning C．Protecting D．Keeping A．回答问题 请阅读下面短文，根据所提供的信息，回答5个问题。要求所写答案语法正确、语义完整切题。 Elephants are the biggest land animals. They are grey. Their skin is thick (厚的). They come from Africa and Asia, but we can also see them in other areas.  African elephants have very big ears while Asian elephants have small ears. Elephants have a very long nose and some have two long white teeth. Elephants eat a lot of food, but they don’t eat meat. They eat leaves, grass and fruit. An elephant eats about 140 kilos of food a day. A big elephant is over 3.5 metres tall and weighs 6,000 kilos. Elephants love water and they are good at swimming. Nowadays, elephants are in danger. They have less and less land to live on, because people are taking away their land and forests. People cut down many trees, so elephants are losing their homes. Also, some people kill elephants to sell their long teeth. Today there are only about 3,000 elephants (over 100,000 before) in the wild. If we don’t protect these wild animals, they will die out soon. So we should help them. In order to protect elephants, we must save the trees and we shouldn’t buy things made of their teeth. 1．Where do elephants come from? 　 2．How much food does an elephant eat a day? 　 3．What are elephants good at? 　 4．Why do some people kill elephants? 　 5．What must we do to protect elephants? 　                                                                                     　   B．书面表达 假设你是约翰，本周英语角的话题是 “My Favourite Animal”。请你根据以下思维导图内容提示用英文写一篇短文，分享你最喜欢的动物。 My Favourite Animal By John    My favourite animal is _________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 1 / 6 学科网（北京）股份有限公司 $ Unit 6 Fantastic friends 第2课时：Understanding ideas(Grammar) 分层作业 核心知识速记 03拓展培优 01基础达标 04思维进阶 02能力提升 词汇 1 beaver /ˈbiːvə/ n. 河狸,海狸 3 engineer /ˌendʒəˈnɪə/ n. 工程师;设计师 2 wolf /wʊlf/ n. 狼 句型 1. 我们在学校为“爱鸟周”活动学习鸟类知识。We're studying birds for Bird Week at school. 2. 我现在正在公园里看鸽子I'm watching pigeons in the park now. 3. 那只鸽子正在水里看自己呢！That pigeon is looking at itself in the water! 4. 看！这只兔子能跳一米高！Look! The rabbit is jumping one metre high! 5. —那匹马在睡觉。—我简直不敢相信。它还站着呢。它能那样睡吗？ —The horse is sleeping. —I can’t believe it. It is standing . Can it sleep like that? 6. 我在看树上的猫。I am watching the cat in the tree. 7. 但它有什么用呢？But what’s it for? 8. 这个池塘会保护他们免受狼、熊等动物的侵害。The pool will protect them from wolves, bears, etc. 1、 单词默写。 1.n. 河狸,海狸 　　　　　  2.n. 狼 　　　　　  3.n. 工程师;设计师 　　　　　  二、词组默写。 1. __________________look like 2 .__________________ protect ... from .... 3.__________________such nice work 4 . __________________nature’s engineers 5. __________________by the river 【答案】1. 看起来像2. 保护……免受……3.多么出色的工作啊！4.大自然的工程师5. 在河边 三、根据要求完成句子 1.但它有什么用呢？But __________ it ________? 2.池塘将保护他们免受狼和狐狸的危害。 The pond will _________ them _________ wolves , foxes,etc. 3. 多么好的杰作啊。It’s _________ _________ _________ . 4.另一只正在试图找到食物。The other one ________ _________to find food. 5.海狸真的是“大自然的工程师”！Beavers are really “ _________ _________”！ 【答案】1 what’s for 2.protect from 3.such nice work 4. is trying 5. nature’s engineers 四 、用括号内所给词的适当形式填空。 1．Now two beavers (swim) in the pond over there. 【答案】are swimming 【详解】句意：现在有两只海狸正在那边的池塘里游泳。根据“Now”以及句子结构可知，此处表示当前正在进行的动作，需用现在进行时。现在进行时的结构为“be+动词的现在分词”，主语two beavers是复数，be动词用are，swim的现在分词形式为swimming。故填are swimming。 2．We don’t like (wolf), because they are scary. 【答案】wolves 【详解】句意：我们不喜欢狼，因为它们很吓人。wolf“狼”，可数名词。根据后文中的“they”可知，空处应用名词复数，把wolf变为wolves。故填wolves。 3．Please tell me the (engineer) names. I need to make sure they are all here for the meeting. 【答案】engineers’ 【详解】句意：请告诉我工程师的名字。我需要确定他们都在这里开会。根据“names”可知，此处指“工程师们的”名字，要用“engineer”的复数形式“engineers”，前后为所属关系，因此使用所有格形式。故填engineers’。 4．It’s very important for us ( protect) the environment. 【答案】to protect 【详解】句意：保护环境对我们来说很重要。根据“It’s important for us…the environment.”可知，这里考查句型“It’s+形容词+for sb.+to do sth.”，意为“做某事对某人来说是……的”，其中it是形式主语，真正的主语是后面的不定式。protect意为“保护”，是动词，故此处用其不定式的形式，故填to protect。 5．Many visitors come to Tibet every year because of its (nature) environment. 【答案】natural 【详解】句意：每年都有许多游客因为西藏的自然环境来到西藏。空处位于名词environment前，填形容词作定语。natural“自然的”。故填natural。 6．Our parents protect us from (get) hurt. 【答案】getting 【详解】句意：我们的父母保护我们免受伤害。固定短语protect sb. from doing sth.表示“保护某人免受某事/做某事之害”，介词from后需接动名词形式，get的动名词形式为getting。故填getting。 7．You should go outdoors to have a walk in (such ) fine weather. 【答案】such 【详解】句意：在这么好的天气里，你应该去户外散步。 8．Look, the girl (fly) a kite. Let’s go and play with her. 【答案】is flying 【详解】句意：看，那个女孩正在放风筝。我们去和她一起玩吧。根据句中“look”可知这是现在进行时态，现在进行时态的句子结构是“be+v-ing”，根据“the girl”可知be动词是“is”，“fly”的现在分词是“flying”。故填is flying。 9．The basketball matches between the teams from the villages are very exciting. Many people (watch) them. 【答案】 are watching 【详解】句意：各村各队之间的篮球比赛非常精彩。许多人在看他们。故填 are watching。 10．We usually stay in when it snows, but now we (build) a snowman outside. 【答案】are building 【详解】句意：下雪时我们通常待在家里，但现在我们正在外面堆雪人。 5、 短文填空 Earlier this year, a family of beavers caught the world’s attention. In just two days, they built a dam (坝) that the Czech government had planned for seven years but never started. Their work saved 1.2 million dollars. People worldwide 1 (impress) by these hard-working animals. But if you know anything about beavers, you may not find the news 2 (surprise). Beavers are like natural engineers. Using strong teeth, beavers cut branches to build dams and homes. They also add grass, rocks, and mud 3 (make) them stronger. Even young beavers help! But why do they build dams? Experts say it’s for safety. On land, beavers move slowly and they’re very likely to be in danger. In the water, they are great 4 (swim) and can hold their breath for 15 minutes. Their dams create ponds that protect them from other animals like bears. Beavers remind us that every creature 5 (play) an important role in nature. By working with these furry engineers, we can protect our environment better. 【答案】1．were impressed 2．surprising 3．to make 4．swimmers 5．plays 【导语】本文主要讲述了海狸作为 “自然工程师” 的能力及其在生态环境中的重要作用。 1．句意：全世界的人们都对这些勤劳的动物印象深刻。句子主语“People worldwide”与谓语“impress”之间为被动关系，表示“被打动”，且根据前文“Earlier this year”可知时态为一般过去时，因此用一般过去时的被动语态“were impressed”。故填were impressed。 2．句意：但如果你对海狸有所了解，可能不会觉得这则新闻令人惊讶。“find + 宾语 + 宾语补足语”结构中，宾语“the news”指物，需用动词-ing形式形容词“surprising”作补足语，说明事物的特征。故填surprising。 3．句意：它们还会添加草、岩石和泥浆，使其更加坚固。句中“add grass, rocks, and mud”的目的是“使它们更坚固”，需用动词不定式“to make”作目的状语。故填to make。 4．句意：在水中，它们是出色的游泳者，能屏住呼吸15分钟。根据“In the water, they are great … (swim) and can hold their breath for 15 minutes.”可知，此处需用名词“swimmer”，主语“they”为复数，故用复数形式“swimmers”。故填swimmers。 5．句意：海狸提醒我们，每个生物在自然界中都扮演着重要角色。根据“every creature … (play) an important role in nature.”可知，宾语从句中“every creature”作主语，意为“每个生物”，为单数概念，且陈述客观事实，因此谓语动词用第三人称单数形式“plays”。故填plays。 6、 阅读理解。 Many people say dolphins are intelligent. They can learn, think, and understand things quickly. Scientists say sometimes dolphins show they are really smart, just like humans (人类). How? Talk Like humans, every dolphin has its “name”. The name is a special whistle (口哨). Every dolphin chooses a whistle as (作为) its name, usually by its first birthday. Dolphins like to “talk” to each other about a lot of things-such as their age, their feelings, and danger around. Understanding dolphin’s talk is not easy for humans. No one can "speak dolphin"yet, but some scientists are trying to learn. Play Dolphins live in groups and they often join other dolphins from different groups to play games and have fun-just like people. Sometimes they run after other dolphins carrying things and throw these things back and forth. Scientists believe playing together is something only intelligent animals do. Teamwork Dolphins and humans are similar (相似的) in another way: They both make plans for getting things they want. In the seas of southern Brazil, for example, dolphins use an intelligent way to get food. When there are fish near a boat, dolphins will signal (示意) to fishermen. With the dolphins’ help, fishermen can catch a lot of fish. In return (回报), dolphins can get some to eat. 1．The underlined word “intelligent” in Paragraph 1 is closest to the meaning of ________. A．funny B．difficult C．smart D．dangerous 2．How does a dolphin get a name? A．By choosing a whistle for itself. B．By talking with each other. C．By having its first birthday. D．By trying to “speak dolphin”. 3．Which of the following can not show dolphins are smart? A．Dolphins “talk” with each other. B．Dolphins live in groups. C．Dolphins help fishermen to get food. D．Dolphins play games with each other. 4．Choose the best title for this passage. A．The Incredible Dolphin B．Dolphins’ Talk C．Intelligent Animals D．Humans’ Friend 【答案】1．C 2．A 3．B 4．A 【导语】本文是一篇说明文，主要从几个方面介绍了海豚的聪明，在某些方面和人类一样。 1．词句猜测题。根据第一段“Many people say dolphins are intelligent. They can learn, think, and understand things quickly.”可知，此处指海豚很聪明，可以很快地学习、思考和理解事物。故划线部分单词intelligent与smart“聪明的”意思接近。故选C。 2．细节理解题。根据第二段“Every dolphin chooses a whistle as its name, usually by its first birthday.”可知，此处指海豚为自己选择一个哨子获得名字的。故选A。 3．推理判断题。根据关于海豚在Talk方面的描述“Dolphins like to ‘talk’ to each other about a lot of things---such as their age, their feelings, and danger around.海豚喜欢互相‘谈论’很多事情”、关于海豚在Play方面的描述“Sometimes they run after other dolphin…playing together is something only intelligent animals do.科学家们认为只有聪明的动物才会一起玩耍”及关于海豚Teamwork方面的描述“dolphins use an intelligent way to get food…With the dolphins’ help, fishermen can catch a lot of fish.海豚用一种聪明的方式获取食物”可知，以上三方面的描述说明海豚很聪明，故选项B“海豚是群居的”表述错误。故选B。 4．最佳标题题。通读全文可知，本文从几个方面介绍了海豚很聪明，它们在某些方面可以和人类一样学习、思考和理解事物。选项A“神奇的海豚”符合题意。故选A。 7、 完形填空。 Animals are our best friends. They are important to us. They 1 together with us on the Earth. We cannot live without animals. So we should take good care of them. Then how can we protect  animals? First ,we should 2 the importance of protecting wild animals. Animals are an important source (来源) of food. Every animal has its place in the balance (平衡) of 3 . If we destroy (破坏) a kind of animal, we will have many other 4 very soon. For example, when farmers 5   a large number of hawks (鹰), the mice will destroy farmers rice. Why? Because hawks eat 6 . Without hawks. the mice will become 7 . Second, let people know how to protect animals - 8 killing wild animals and protect their 9 . If we see other people destroy animals homes, we should stop them. 10 wild animals is the duty of each of us. Let s protect animals together！ 1．A．work B．study C．live D．play 2．A．understand B．complete C．forget D．win 3．A．time B．nature C．history D．weather 4．A．ideas B．dreams C．grammars D．problems 5．A．save B．buy C．kill D．feed 6．A．mice B．rice C．grass D．leaves 7．A．more and more B．less and less C．higher and higher D．smaller and smaller 8．A．enjoy B．stop C．keep D．practise 9．A．friends B．food C．babies D．homes 10．A．Sharing B．Cleaning C．Protecting D．Keeping 【答案】1-5 CABDC 6-10 AABDC 【分析】这篇短文主要是介绍了保护野生动物的重要性、如何保护野生动物以及呼吁大家一起来保护野生动物。 1．句意：他们和我们一起住在地球上。 本题考查动词辨析及语境理解。A. work工作；B. study学习；C. live    居住；D. play玩。根据后文We cannot live without animals.可知人类与动物一起居住在地球上。故选C。 2．句意：首先，我们应该了解保护野生动物的重要性。 本题考查动词辨析及语境理解。A. understand了解；B. complete完成；C. forget忘记；D. win赢得。understand the importance of 了解……的重要性，故选A。 3．句意：每种动物在自然界的平衡中都有自己的位置。 本题考查名词辨析及语境理解。A. time时间；B. nature自然；C. history历史；D. weather天气。根据后文可知人与自然的平衡，故选B。 4．句意：如果我们破坏了一种动物，我们很快就会许多有其他问题。 本题考查名词辨析及语境理解。A. ideas想法；B. dreams梦；C. grammars    语法；D. problems问题。根据后文的举例子可知，一种动物的变少时，会引起其他的问题。故选D。 5．句意：例如，当农民杀死大量的鹰，老鼠会破坏农民的大米。 本题考查动词辨析及语境理解。A. save救；B. buy    买；C. kill杀害；    D. feed喂。这里与上文的destroy对应，所以用kill。故选C。 6．句意：为什么？因为鹰吃老鼠。 本题考查名词辨析及语境理解。A. mice老鼠；B. rice米；C. grass草；D. leaves叶子。根据后文Without hawks. the mice will become ___7___.可知是鹰吃老鼠。故选A。 7．句意：没有鹰，老鼠就会越来越多。 本题考查形容词比较级及语境理解。A. more and more越来越多；B. less and less越来越少；C. higher and higher越来越高；    D. smaller and smaller越来越小。根据前文可知没有鹰吃老鼠，老鼠当然会越来越多。故选A。 8．句意：第二，让人们知道如何保护动物——停止杀害野生动物，保护它们的家园。 本题考查动词辨析及语境理解。A. enjoy喜欢；    B. stop停止；C. keep保持；D. practise练习。结合句意可知是停止杀害野生动物。故选B。 9．句意：第二，让人们知道如何保护动物——停止杀害野生动物，保护它们的家园。 本题考查名词辨析及语境理解。A. friends朋友；B. food食物；C. babies婴儿；    D. homes家。根据后文If we see other people destroy animals homes, we should stop them.可知是不要破坏动物的家园。故选D。 10．句意：野生动物是我们每个人的责任。 本题考查动词辨析及语境理解。A. Sharing分享；    B. Cleaning打扫干净；C. Protecting保护；D. Keeping保持。根据后文可知这里是在呼吁大家保护野生动物。故选C。 A．回答问题 请阅读下面短文，根据所提供的信息，回答5个问题。要求所写答案语法正确、语义完整切题。 Elephants are the biggest land animals. They are grey. Their skin is thick (厚的). They come from Africa and Asia, but we can also see them in other areas.  African elephants have very big ears while Asian elephants have small ears. Elephants have a very long nose and some have two long white teeth. Elephants eat a lot of food, but they don’t eat meat. They eat leaves, grass and fruit. An elephant eats about 140 kilos of food a day. A big elephant is over 3.5 metres tall and weighs 6,000 kilos. Elephants love water and they are good at swimming. Nowadays, elephants are in danger. They have less and less land to live on, because people are taking away their land and forests. People cut down many trees, so elephants are losing their homes. Also, some people kill elephants to sell their long teeth. Today there are only about 3,000 elephants (over 100,000 before) in the wild. If we don’t protect these wild animals, they will die out soon. So we should help them. In order to protect elephants, we must save the trees and we shouldn’t buy things made of their teeth. 1．Where do elephants come from? 　 2．How much food does an elephant eat a day? 　 3．What are elephants good at? 　 4．Why do some people kill elephants? 　 5．What must we do to protect elephants? 　                                                                                     　   B．书面表达 假设你是约翰，本周英语角的话题是 “My Favourite Animal”。请你根据以下思维导图内容提示用英文写一篇短文，分享你最喜欢的动物。 My Favourite Animal By John    My favourite animal is _________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ ____________________________________________________________________________________________ 【答案】1．They come from Africa and Asia. 2．An elephant eats about 140 kilos of food a day. 3．They are good at swimming. 4．Some people kill elephants to sell their long teeth. 5．We must save the trees and we shouldn’t buy things made of their teeth. 例文 My Favourite Animal By John My favourite animal is the elephant. Elephants are very big and smart animals. They have grey skin and a very long nose. Some of them have two long white teeth. I like elephants because they are very friendly to humans. They can help people do a lot of things. They are also very cute and lovely. They are important to our environment. We should protect them and let them live happily in the wild. 【导语】本文主要介绍了大象的特征、生活习性、所面临的危险以及如何保护它们。 1．根据文章“Elephants...come from Africa and Asia”可知，大象主要生活在非洲和亚洲，故填They come from Africa and Asia. 2．根据文章“An elephant eats about 140 kilos of food a day”可知，大象每天大约吃140公斤食物，故填An elephant eats about 140 kilos of food a day. 3．根据文章“Elephants love water and they are good at swimming”可知，大象喜欢水，并且擅长游泳，故填They are good at swimming. 4．根据文章“some people kill elephants to sell their long teeth”可知，有些人为了卖大象的长牙而猎杀它们，故填Some people kill elephants to sell their long teeth. 5．根据文章“In order to protect elephants, we must save the trees and we shouldn’t buy things made of their teeth”可知，为了保护大象，我们必须保护树木，并且不购买象牙制品，故填We must save the trees and shouldn’t buy things made of their teeth. 1 / 6 学科网（北京）股份有限公司 $