Unit 5 Play by the rules-2026-2027学年八年级英语上册语法专项（外研版）

Unit 5 Play by the rules? 语法专项 章 语法概览 ★动词不定式表目的 ★不定式表目的与for/so that表目的的转换 语法精讲精练一 1.动词不定式表目的的定义与功能 定义：动词不定式(to+动词原形)在句中作目的状语，用来表示某一动作发生的目的或 意图，回答“为什么做某事？”(Wy)的问题。 核心考点：不定式表目的时，在句中只能作状语，不能作谓语或宾语，且逻辑主语通常是 句子的主语。 2.动词不定式表目的的基本用法（三大核心考点） 用法 结构 例句 注意点 不定式与谓语动作有先后 ①置于句末 主语+谓语+宾语+ I went to the library to 顺序（先“去”，后 (最常见) to do... borrow some books. “借”) ②置于句首 To catch the early bus,he 逗号隔开，不定式的逻辑 (强调目 T0d0.,主语+谓语. 主语仍是句子主语 的) got up at 5:00. ③与疑问词 连用(“做 主语+谓语+疑问词+ She doesn't know what to 疑问词+不定式作宾语， 什么”的目 to do... do next. 但整体仍表目的含义 的) 中考高频考点：不定式表目的时，不可用for doing替代（除非是固定搭配）。 例：I came here to see you.(W) I came here for seeing you.(x) 但：I came here for a meeting.(for+名词，可以) 3.常见动词搭配（不定式表目的） 动词 搭配结构 例句 go come/ go to do come to do leave to do He left early to catch the train. leave use/need/ use sth.to do/need to do /want to do I use a knife to cut the apple. want stop /try She stopped to have a rest.(停下（原来 stop to do /try to do learn to do learn 事)去做某事) 易混辨析： stop to do:停下来去做另一件事（目的） stop doing:停止正在做的事 例：He stopped to smoke.(他停下来去抽烟) He stopped smoking.(他戒烟了) 4.易混考点辨析（中考必考） (1)不定式表目的vs介词for+动名词 不定式：强调动作的目的，后接动词原形 for+doing:强调用途或功能，后接动名词 例：This machine is used to cut paper.(目的是切纸) This machine is used for cutting paper.(用途是切纸) 考点：两者有时可互换，但单选题常考搭配：use sth.todo/be used for doing (2)不定式表目的vs动词原形祈使句 不定式：不能单独作谓语，需依附于主句 祈使句：用动词原形开头，表命令或建议 例：To get good grades,.you must study hard..（目的状语) Get good grades!(祈使句) 考点：语法填空易混淆：若句中已有谓语，则用todo表目的：若没有谓语，则用动词原形 (祈使句)。 (3)不定式表目的vs结果状语(too.to/enough to) 目的状语：todo表示“为了…” 结果状语：to0+adj.+todo（太…而不能…)或adj.+enough+todo（足够…而 能…) 例：She ran fast to catch the bus.(为了赶车) She ran too slowly to catch the bus.(太慢而没赶上) 考点：中考常将两者放在同一题干中，让学生根据语境判断。 二、专项训练（中考/名校月考难度，8-10题/大题，共3大题） （一)单项选择 1.-Why did you go to the supermarket? A.Buy B.To buy C.Buying D.Bought 2.The doctor told him more water every day. A.drink B.drinking C.to drink D.drank 3.She got up early the first bus. A.catch B.catching C.to catch D.caught 4.-What do you want when you grow up? A.be B.being C.to be D.been 5.The little boy stopped and ran to his mother. A.cry B.crying C.to cry D.cried 6.-Why did you come here? A.show B.to show C.showing D.showed 7.He used his knife the box open. A.to cut B.cutting C.cut D.cuts 8.My parents often tell me too much time on computer games A.not spend B.not to spend C.don't spend D.to not spend 9. the truth,she decided to tell her parents everything. A.Tell B.Telling C.To tell D.Told 10.The machine is used the floor. A.to clean B.for clean C.cleaning D.cleaned (二)语法填空 阅读下面短文，在空白处填入括号内所给单词的适当形式，使短文通顺、完整。 Last summer,I went to the library 1. (borrow)some books.On the way,I saw an old woman 2. (ty)to cross the road.She looked wonied.I stopped 3. (help)her.She smiled and said thanks The next day,I decided 4. (visit)my grandma.She lives in a small village.I took a bus 5. (get)there.When I arived,she was cooking.She asked me 6. (stay)for lunch.We had a great time together. After lunch,I helped her 7. (water)the flowers in the garden.She told me that she plants flowers 8. (make)her home beautiful.I learned a lot from her. I think it's important 9. (spend)time with family.Everyone should try 10. (be)kind to others. (三)完成句子 l.他早起是为了赶上第一班火车。He got up early the first train 2.我使用这把剪刀来剪纸。I use this pair of scissors paper. 3.她停下来喝了一杯水。She stopped a glass of water. 4.为了通过考试，他每天晚上努力学习。 the exam,he studies hard every night. 5,老师告诉我们不要在走廊里跑。The teacher told us in the hallway. 6.我不知道下一步该做什么。I don't know next. 7.这个图书馆是用来读书的，不是用来玩耍的。This library is used not for playing. 8.他太累了，无法继续走路。Hes tured on walking 9.妈妈让我去超市买些鸡蛋。Mom asked me some eggs in the supermarket. 10.为了保持健康，我们应该每天锻炼。 healthy,we should exercise every day. 三、参考答案 (一)单项 1.B;2.C;3.C;4.C;5.B;6B;7.A;8.B;9.C;10.A 选择 (二)语法 1.to borrow 2.trying ;3.to help 4.to visit 5.to get 6.to stay 7.(to)water 8.to 填空 make 9.to spend 10.to be (三)完成 1.to catch 2.to cut 3.to drink 4.To pass 5.not to run 6.what to do 7.for 句子 reading ;8.too;to go 9.to buy 10.To keep 章 语法精讲精练二 1.不定式表目的的基本用法 不定式(to+动词原形)在句中作目的状语，表示“为了做某事”，意思相当于“in order to”。 功能 结构 例句 翻译 目的状语 I went to the library to 我去图书馆是为了借 to+动词原形 borrow a book. 本书。 She got up early in 她早起是为了赶上第 强调目的（更正式） in order to+动词原形 order to catch the first 一班车。 bus in order not to so as 他早早离开以免错过 否定式 He left early so as not not to+动词原形 to miss the train. 火车。 注意：不定式作目的状语时，不能用于否定形式“not to do”直接作目的，需用“in order not to或“s0 as not to”。 2.for表目的的用法 for是介词，后跟名词或动名词(doing),表示目的的几种常见情况： 结构 用法 例句 翻译 He saved money for a 他存钱是为了买一辆 for+名词 为了某物/某人 new bike. 新自行车。 为了做某事（常见于 This knife is used for 这把刀是用来切面包 for+动名词 用途说明) cutting bread. 的。 for+名词/代词+to 为了某人做某事 I bought a gift for you 我买了一份礼物让你 do to give to your mother. 送给你妈妈。 注意：当目的明确指向某个动作时，通常用不定式(todo);当目的指向某物或用途时， 常用for+名词/动名词。 3.so that表目的的用法 so that引导目的状语从句，意为“为了…，以便…”。从句中常出现情态动词can/ could/may/might will /wouldo 结构 时态要求 例句 翻译 so that+主语+can/ 主句为一般现在时/ She studies hard so that 她努力学习以便能通 wl+动词原形 将来时 she can pass the exam. 过考试。 so that+主语+ He got up early so that 他早起是为了赶上火 could/would+动词 主句为一般过去时 he could catch the 车。 原形 train. so that+主语+ 我们早早离开以免错 so that否定形式 won't/wouldn't+动 We left early so that we 过公交车。 词原形 wouldn't miss the bus. 4.三种结构的转换规则（中考核心考点） 原结构 转换结构 转换方法 如果目的直接指向某物，可 互换。例：e went to the to do for+名词 store to buy a pen.He went to the store for a pen. 加主语，todo动词变谓语， 加ca/could/will/would。 to do so that+从句 例：I called her to invite her..→ I called her so that I could invite her. 如果名词可转换为动作，可 for+名词 互换。例：She saved money to do for a trip.-She saved money to take a trip. 去掉主语和情态动词，变成 不定式。例：He turned on the so that+从句 to do light so that he could see clearly. >He turned on the light to see clearly. 同样加主语和情态动词。 例：She exercises in order to in order to do so that+从句 keep fit.She exercises so that she can keep fit. 直接用否定不定式。例：He spoke softly so that he wouldn't so that否定式 in order not to do wake her.He spoke softly in order not to wake her. 注意：转换时要注意保持主句和从句的主语一致；so that从句中的情态动词要根据句意和 时态选择正确形式。 5.易混点辨析（中考必考） (1)todo表目的vs.不定式作宾语 表目的：I went there to see you.(我去那里是为了看你) 作宾语：I want to see you..(我想见你)一此处to see是want的宾语，不是目的状语 (2)for+名词vs.for+动名词 for+名词：表示为了获得某物 for+动名词：表示用途或功能 例：I came here for water..(我来这里是为了水。) This machine is used for checking quality.(这台机器用于检查质量。) (3)so that vs.so...that so that表目的：为了… so..that表结果：如此…以至于… 易错：He studied hard so that he could pass the exam.(目的) He studied so hard that he passed the exam(结果) (4)否定目的的表达 不定式否定：in order not to/so as not to(不常用not to) for否定：for+名词前加not,但较少见 so that否定：so that+主语+won't/wouldn't/can't/couldn't 二、专项训练 (一)单项选择（共10题） 从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。 1.She got up early the early bus A.catch B.to catch C.for catch D.catching 2.I called my mother her about my school trip A.tell B.telling C.to tell D.for tell 3.He saved his money a new computer. A.to buying B.for buy C.to buy D.for buying 4.The teacher spoke loudly everyone could hear her A.so that B.in order C.for D.so as 5.We went to the park a picnic last Sunday. A.have B.to have C.for having D.having 6.He closed the window the cold air out. A.keep B.to keep C.for keep D.keeping 7.She studied hard she could get into a good school. A.so that B.so C.in order to D.to 8.I need a pair of scissors the paper. A.cut B.cutting C.to cut D.for cut 9.They left early miss the game. A.not to B.so as not to C.so that D.for not 10. get better grades,he does lots of exercises every day. A.In order to B.So that C.For D.To (二)语法填空（共10空） 阅读下面短文，在空白处填入括号内所给单词的适当形式，或填入适当的词（每空一 词)，使短文通顺、完整。 Last Sunday,I went to the city library 1. (borrow)some books on science.I wanted 2. (learn)more about space.On my way,I met my friend Tom.He was going to the store 3. (buy)a new pen.We decided to go together 4. that we could save time In the library,I found a book 5. (call)The Stars.I took it home 6. (read) it carefully.The next day,I told my classmate Lily about it.She said she needed a book 7. (help)with her report.So I lent her my book 8. she could finish her work After school,my mother asked me 9. (help)her cook dinner.I also called my dad 10. (tell)him dinner would be ready at 6:00. (三)完成句子（共10题) 1.他每天跑步是为了保持健康。 He runs every day 2.她大声说话以便让所有人都能听到。 She spoke loudly everyone hear her. 3.我买了一些花送给妈妈。 I bought some flowers my mother. 4.为了通过考试，他学习非常努力。 pass the exam,he studies very hard. 5这把刀是用来切水果的。 This knife is used fruit. 6.他早起以免迟到。 He got up early be late 7.我们去车站接朋友。 We went to the station our friend. 8为了能赶上火车，她提前一小时到达了车站。 She arrived at the station an hour early she catch the train 9.我写信是为了邀请你参加我的生日聚会。 I wrote a letter you my birthday party. 10.他存钱是为了买一辆自行车。 He saved money a bike 三、参考答案 (一)单项 选择 1.B;2.C;3.C4.A;5.B;6.B;7.A;8.C;9.B;10.A (二)语法 1.to borrow 2.to leam 3.to buy 4.so ;5.called 6.to read 7.to help ;8.so