Unit5 Saving animals in danger 重点语法：it作形式主语和enough to do精讲精练-2025-2026学年八年级英语下册重难点讲练全攻略（新教材沪教版）

**基本信息** 以“核心总表+易错细分+专项精练”构建语法突破体系，系统整合it作形式主语与enough to do的用法规则、易错辨析及中考应用，助力语言能力与思维品质提升。 **专项设计** |模块|题量/典例|方法提炼|知识逻辑| |----|-----------|----------|----------| |语法知识精讲|核心总表（2类语法点）、易混细分表（2类易错点）|提炼核心结构（如It+be+adj+to do）、关键用法（enough位置规则）、易错对比（for/of辨析）及记忆技巧（“形副后，名前”）|从总述核心用法到细分易错点，形成“概念-规则-辨析”递进链条| |语法知识精练|40题（覆盖it作形式主语3类结构、enough to do 3类考法）|通过题目强化规则应用，针对中考高频考点（如enough位置、否定式too...to）设计训练|从基础应用到综合辨析，匹配中考命题趋势，实现知识迁移|

2025-2026学年一线教师制作新教材英语同步精品系列资料，名师遴选！ 2025-2026学年一线教师制作新教材英语同步精品系列资料，名师遴选！ 学校:___________姓名：___________班级：___________考号：___________ Unit5 Saving animals in danger 重点语法：it作形式主语和enough to do精讲精练 语法知识精讲 一、核心总表（用法全总结，中考高频） 两大语法核心提醒：it作形式主语仅起替代作用，真正主语后置；enough to do表“足够……去做某事”，enough的位置的是核心考点。 语法类型 核心结构 核心含义/作用 关键用法 经典例句 （含易错对比） it作形式主语 1. It+be+形容词+(for sb)+to do sth 2. It+be+名词+(for sb)+to do sth 3. It+动词（seem/appear等）+ that从句 it无实际含义，替代后置的真正主语（to do sth/that从句），避免句子头重脚轻 1. it不可省略，不能用其他代词替代； 2. for sb可省略，根据句意判断是否需要； 3. 形容词修饰人时用of sb（如kind） 1. It is important (for us) to study hard.（正确） 2. To study hard is important.（语法正确，但不常用） 3. It seems that he is ill.（that从句作真正主语） enough to do 1. 形容词/副词+enough+to do sth 2. 名词+enough+to do sth 表示“某人/某物足够……，可以做某事”，表肯定含义 1. enough修饰形容词/副词，放其后； 2. enough修饰名词，放其前； 3. 否定式常用too...to...（太……而不能……） 1. He is tall enough to reach the book.（正确） 2. He is enough tall to reach...（错误） 3. He has enough time to finish it.（enough修饰名词） 二、易混重点细分表（中考必考辨析） 1. it作形式主语的易错辨析 易错点类型 错误用法（×） 正确用法（√） 中考考点提醒 it与其他代词混淆 He is important to study hard. It is important to study hard. 形式主语只能用it，不能用he/she/this等 for sb与of sb混淆 It is kind for you to help me. It is kind of you to help me. 形容词修饰人用of sb，修饰事情用for sb 真正主语位置错误 It is important to study hard is necessary. It is important that to study hard is necessary.（或简化句式） 真正主语只能是to do或that从句，不可重复 2. enough to do 易错辨析（中考最高频） 修饰对象 错误用法（×） 正确用法（√） 记忆技巧 形容词（如tall） She is enough tall to play basketball. She is tall enough to play basketball. 形副后，名前 名词（如money） He has money enough to buy a book. He has enough money to buy a book. enough修饰名词放前面 否定含义表达 He is not tall enough to reach it.（语法对，不常用） He is too short to reach it.（中考首选表达） 否定用too...to...更自然 语法知识精练 1．It’s ________ to help people in need. A．bad B．easy C．meaningful D．small 2．It is great for us ________ the world without going out. A．visit B．to visit C．visiting D．visited 3．It’s our duty ________ our parents with housework. A．help B．helping C．to help D．helped 4．It is very difficult ________ astronauts to live in space for a long time. A．for B．of C．with D．by 5．—I’m afraid I can’t finish the task on time. —Don’t worry. You are ________ to ask for help if needed. A．too brave B．brave enough C．enough brave D．so brave 6．—Are you satisfied with your English exam result? —Yes, I think I was _______ to get full marks. A．luck enough B．lucky enough C．enough luck D．enough lucky 7．The little boy is ________ to go to school. He is too young. A．enough old B．old enough C．not old enough D．enough not old 8．I used to be shy, but now I’m brave enough ________ a speech in front of the class. A．give B．to give C．giving D．gave 9．—Why didn’t you stop the boy from throwing rocks at the duck? —Because I was not ________ to argue with him at that time. A．enough brave B．brave enough C．enough bravely D．bravely enough 10．The rescue team worked day and night, and finally the injured crane was ________ to fly back to the wild. A．enough strong B．strongly enough C．strong enough D．enough strongly 11．Tao Yuanming’s simple and direct writing style was different from that of his time. He was ________ the rules. A．too brave to break B．too brave to follow C．brave enough to follow D．brave enough to break 12．I’m sure he can run ________ to win first prize. A．enough fast B．fast enough C．too fast D．so fast 13．Jenny works ________ a kindergarten teacher, and she is ________ to stay with naughty kids all day long. A．for, patient enough B．for; enough patient C．as; patient enough D．as; enough patient 14．You are not ________ to enter the teachers’ office without knocking at the door first. A．enough polite B．polite enough C．too polite D．polite too 15．I find these picture books ________ for my three-year-old daughter to read. A．easily enough B．too easy C．easy enough D．difficult enough 16．—Can you understand me, Tony? —Yes, madam. You speak ______. I can follow you. A．clear enough B．enough clear C．clearly enough D．enough clearly 17．He is __________ to go to school by himself. He is already 12. A．too old B．enough old C．old enough D．so old 18．The baby elephant is not strong ________ to protect itself from dangerous hunters. A．enough B．too C．very D．so 19．The girl is ________ to help her classmates with their English studies. A．enough kind B．kind enough C．too kind D．kind too 20．The man was trustworthy ________ to win the trust of all the people around him. A．too B．enough C．so D．such 21．In many countries, people are _________ follow others instead of pushing past them when walking on crowded streets. A．too polite to B．so polite that C．polite enough to D．polite enough that 22．The new rule about school manners is _________ understand. Even the new students can follow it easily. A．too clear to B．clear enough to C．too difficult to D．difficult enough 23．Parents can give advice when needed, but ________ is up to us to decide how to spend our pocket money. A．this B．that C．it D．these 24．________ relaxing for us to spend some time in the countryside on weekends. A．It’s B．That’s C．This is D．There’s 25．It’s very kind ________ you ________ your free time to look after the sick kids in the hospital. A．of; to spend B．for; to spend C．of; spending D．for; spending 26．—What do you think is a good way for us students to keep healthy? —It is important ________ students ________ part in outdoor activities. A．for; to taking B．for; to take C．of; to taking D．of; to take 27．With the help of the volunteer guide, ________ is easy for the blind people to walk around the park safely. A．that B．it C．them D．this 28．When you find ________ in front of the Grand Canyon, you’ll find ________ hard to describe its grandeur in words. A．you; it B．you; it’s C．yourself; it D．yourself; itself 29．It’s not good ________ too much time on online shopping. A．waste B．to waste C．wasting D．wasted 30．________ our duty ________ the classroom clean. A．It’s; keep B．That’s; to keep C．It’s; to keep D．It’s; keeping 31．—How generous it is ________ him to give all his pocket money to the poor! —Yes, he is a kind boy. A．for B．of C．to D．with 32．It ________ ten years since the first generation of Huawei smartwatches ________ on the market. A．was; came B．was; has come C．has been; came D．has been; has come 33．It’s meaningful ________ more classic books in our free time. A．read B．to read C．reading D．reads 34．________ is necessary for teenagers to learn about nature and the environment. A．This B．That C．It D．What 35．It’s rude ________ laugh at others when they make mistakes. A．of you to B．for you to C．of you D．for you 36．—Jack was too nervous to ________ himself ________. —Exactly, he didn’t have ________. A．explain; enough clearly; enough confidence B．express; clearly enough; enough confidence C．explain; clearly enough; confidence enough D．express; enough clearly; confidence enough 37．The boy is only 7 years old. He isn’t ________ to take care of ________. A．old enough; himself B．enough old; himself C．old enough; him D．enough old; him 38．Because of AI tools like DeepSeek, ________ is possible for us to find out many answers without using search engines. A．that B．it C．them D．this 39．________ is wrong of us ________ products made from animals in danger, and ________ is our duty ________ them. A．It; to buy; it; to protect B．It; buying; that; protecting C．That; to buy; it; to protect D．That; buying; that; protecting 40．We all thought ________ necessary for you to spend as much time as you could ________ English. A．that; improving B．it is; to improve C．it; improve D．it was; improving 4 同步新教材，周周有练习，月月有重点！ 5 同步新教材，周周有练习，月月有重点！ 学科网（北京）股份有限公司 $ 2025-2026学年一线教师制作新教材英语同步精品系列资料，名师遴选！ 2025-2026学年一线教师制作新教材英语同步精品系列资料，名师遴选！ 学校:___________姓名：___________班级：___________考号：___________ Unit5 Saving animals in danger 重点语法：it作形式主语和enough to do精讲精练 语法知识精讲 一、核心总表（用法全总结，中考高频） 两大语法核心提醒：it作形式主语仅起替代作用，真正主语后置；enough to do表“足够……去做某事”，enough的位置的是核心考点。 语法类型 核心结构 核心含义/作用 关键用法 经典例句 （含易错对比） it作形式主语 1. It+be+形容词+(for sb)+to do sth 2. It+be+名词+(for sb)+to do sth 3. It+动词（seem/appear等）+ that从句 it无实际含义，替代后置的真正主语（to do sth/that从句），避免句子头重脚轻 1. it不可省略，不能用其他代词替代； 2. for sb可省略，根据句意判断是否需要； 3. 形容词修饰人时用of sb（如kind） 1. It is important (for us) to study hard.（正确） 2. To study hard is important.（语法正确，但不常用） 3. It seems that he is ill.（that从句作真正主语） enough to do 1. 形容词/副词+enough+to do sth 2. 名词+enough+to do sth 表示“某人/某物足够……，可以做某事”，表肯定含义 1. enough修饰形容词/副词，放其后； 2. enough修饰名词，放其前； 3. 否定式常用too...to...（太……而不能……） 1. He is tall enough to reach the book.（正确） 2. He is enough tall to reach...（错误） 3. He has enough time to finish it.（enough修饰名词） 二、易混重点细分表（中考必考辨析） 1. it作形式主语的易错辨析 易错点类型 错误用法（×） 正确用法（√） 中考考点提醒 it与其他代词混淆 He is important to study hard. It is important to study hard. 形式主语只能用it，不能用he/she/this等 for sb与of sb混淆 It is kind for you to help me. It is kind of you to help me. 形容词修饰人用of sb，修饰事情用for sb 真正主语位置错误 It is important to study hard is necessary. It is important that to study hard is necessary.（或简化句式） 真正主语只能是to do或that从句，不可重复 2. enough to do 易错辨析（中考最高频） 修饰对象 错误用法（×） 正确用法（√） 记忆技巧 形容词（如tall） She is enough tall to play basketball. She is tall enough to play basketball. 形副后，名前 名词（如money） He has money enough to buy a book. He has enough money to buy a book. enough修饰名词放前面 否定含义表达 He is not tall enough to reach it.（语法对，不常用） He is too short to reach it.（中考首选表达） 否定用too...to...更自然 语法知识精练 1．It’s ________ to help people in need. A．bad B．easy C．meaningful D．small 【答案】C 【详解】句意：帮助有需要的人是有意义的。 考查形容词辨析。bad（坏的）；easy（容易的）；meaningful（有意义的）；small（小的）。根据常识和语境，帮助有需要的人通常被认为是积极、有意义的行为。故选C。 2．It is great for us ________ the world without going out. A．visit B．to visit C．visiting D．visited 【答案】B 【详解】句意：对我们来说，足不出户游览世界是很棒的。 visit参观，动词原形；to visit去参观，动词不定式；visiting参观，现在分词/动名词；visited参观了，动词过去式/过去分词。根据“It is great for us…the world without going out.”可知，此处为固定句型It is+adj.+for sb.+to do sth.，意为“对某人来说做某事是……的”，其中It是形式主语，真正的主语是动词不定式。应填to visit。 3．It’s our duty ________ our parents with housework. A．help B．helping C．to help D．helped 【答案】C 【详解】句意：帮助父母做家务是我们的责任。 固定句型“It’s+名词+to do sth.”，意为“做某事是……”，其中It是形式主语，动词不定式是真正主语。 4．It is very difficult ________ astronauts to live in space for a long time. A．for B．of C．with D．by 【答案】A 【详解】句意：对于宇航员来说，在太空生活很长时间是非常困难的。 for对于；of……的；with和……一起；by通过。“It’s+adj.+for/of sb. to do sth.”是固定句型，意为“对于某人来说，做某事是……的”，在该句型中，当形容词是描述事物性质时，介词用for。此处形容词是difficult，介词应用for。 5．—I’m afraid I can’t finish the task on time. —Don’t worry. You are ________ to ask for help if needed. A．too brave B．brave enough C．enough brave D．so brave 【答案】B 【详解】句意：——恐怕我不能按时完成任务。——别担心。如果需要的话，你有足够的勇气寻求帮助。 enough修饰形容词或副词时应置于被修饰词之后，即“形容词/副词+enough”，排除C；too... to...表示“太……而不能……”，含否定意味，不符合安慰的语境，排除A；so通常与that从句连用，排除D。根据句意表示“足够勇敢去做某事”，应用brave enough结构。 6．—Are you satisfied with your English exam result? —Yes, I think I was _______ to get full marks. A．luck enough B．lucky enough C．enough luck D．enough lucky 【答案】B 【详解】句意：——你对你的英语考试成绩满意吗？——是的，我想我足够幸运得了满分。 was是系动词，后接形容词作表语，luck是名词，lucky是形容词；enough修饰形容词时要后置，即“形容词+enough”，应填lucky enough。 7．The little boy is ________ to go to school. He is too young. A．enough old B．old enough C．not old enough D．enough not old 【答案】C 【详解】句意：这个小男孩年纪太小，还不能去上学。他太年幼了。 enough old语法错误；old enough足够大；not old enough年龄不够大；enough not old语法错误。“enough”作副词修饰形容词时，要放在形容词之后，根据“He is too young.”可知，小男孩年纪太小，不能去上学，“not old enough”符合语境。 8．I used to be shy, but now I’m brave enough ________ a speech in front of the class. A．give B．to give C．giving D．gave 【答案】B 【详解】句意：我过去很害羞，但现在我足够勇敢可以在全班面前发表演讲了。 考查非谓语动词的用法。enough修饰形容词时要后置，且后面接动词不定式to do something，表示“足够……去做某事”。根据“brave enough”可知后面应用动词不定式to give。故选B。 9．—Why didn’t you stop the boy from throwing rocks at the duck? —Because I was not ________ to argue with him at that time. A．enough brave B．brave enough C．enough bravely D．bravely enough 【答案】B 【详解】句意：——你为什么没有阻止那个男孩向鸭子扔石头？——因为那时我没有足够勇敢去和他争论。   根据语法规则，enough修饰形容词时需后置，可排除A、C；句中“was”是系动词，后接形容词作表语，brave是形容词，bravely是副词，因此排除D。brave enough符合语法及语境。 10．The rescue team worked day and night, and finally the injured crane was ________ to fly back to the wild. A．enough strong B．strongly enough C．strong enough D．enough strongly 【答案】C 【详解】句意：救援队日夜奋战，最终这只受伤的鹤足够强壮，可以飞回野外了。 be动词was后接形容词作表语，且enough修饰形容词时需后置，用strong enough。 11．Tao Yuanming’s simple and direct writing style was different from that of his time. He was ________ the rules. A．too brave to break B．too brave to follow C．brave enough to follow D．brave enough to break 【答案】D 【详解】句意：陶渊明朴素直接的写作风格与他那个时代的风格不同。他足够勇敢去打破规则。 too brave to break太勇敢以至于不能打破规则；too brave to follow太勇敢以至于不能遵守规则；brave enough to follow足够勇敢去遵守规则；brave enough to break足够勇敢去打破规则。根据“was different from that of his time”可知他的风格与众不同，推断他是打破规则，排除遵守规则的选项；too…to…表示“太……而不能……”，brave enough to…表示“足够勇敢去……”，应填brave enough to break。 12．I’m sure he can run ________ to win first prize. A．enough fast B．fast enough C．too fast D．so fast 【答案】B 【详解】句意：我确信他能够跑得足够快来赢得一等奖。 enough修饰形容词或副词时，要放在形容词或副词的后面，“fast”是副词，表示“快地”，所以“足够快”应该是“fast enough” 。而“too fast”表示“太快”，“so fast”表示“如此快”，均不符合句子要表达的“能赢得一等奖，即速度足够快”这一语境。应填fast enough。 13．Jenny works ________ a kindergarten teacher, and she is ________ to stay with naughty kids all day long. A．for, patient enough B．for; enough patient C．as; patient enough D．as; enough patient 【答案】C 【详解】句意：珍妮是一名幼儿园老师，她有足够的耐心整天和淘气的孩子们待在一起。 work for为……工作；work as作为……工作。根据“a kindergarten teacher”可知，此处表示作为幼儿园老师工作，应填as；patient耐心的，形容词；enough足够，副词，修饰形容词时要后置，故第二空应是patient enough。 14．You are not ________ to enter the teachers’ office without knocking at the door first. A．enough polite B．polite enough C．too polite D．polite too 【答案】B 【详解】句意：你不先敲门就进入教师办公室是不够礼貌的。 enough修饰形容词或副词时，需放在被修饰词之后，构成“形容词/副词+enough”结构，too作副词时，放在形容词前。选项A和D语序错误，enough应置于polite之后；选项C语意不符合语境。根据语法规则及句意，此处表示“不够礼貌”，应用polite enough。 15．I find these picture books ________ for my three-year-old daughter to read. A．easily enough B．too easy C．easy enough D．difficult enough 【答案】C 【详解】句意：我发现这些图画书足够简单，适合我三岁的女儿阅读。 easily enough轻而易举；too easy太简单，常用于too...to...结构；easy enough足够简单；difficult enough足够难。find后接宾语再加形容词作宾补，排除副词easily；too...to...结构表否定含义 “太简单而不能读”，不符合语境；根据语境“给三岁女儿读”可知，书应该是足够简单的。故选C。 16．—Can you understand me, Tony? —Yes, madam. You speak ______. I can follow you. A．clear enough B．enough clear C．clearly enough D．enough clearly 【答案】C 【详解】句意：——Tony，你能听懂我说的话吗？——是的，女士，你说得足够清楚，我能跟上你。 考查副词辨析及enough的用法。clear清楚的，形容词；clearly清晰地，副词。修饰动词speak应该使用副词clearly，排除A和B；enough修饰副词时需放在副词之后，排除D，clearly enough符合句意。 17．He is __________ to go to school by himself. He is already 12. A．too old B．enough old C．old enough D．so old 【答案】C 【详解】句意：他足够大了可以自己上学了。他已经12岁了。 too old意为“太大”，通常用于描述年龄过大而不适合做某事；enough old结构错误，enough修饰形容词时应放在其后；old enough意为“足够大”，符合句意；so old意为“如此大”，通常用于强调年龄之大，但此处强调的是他具备自己上学的条件，即年龄足够大。根据“He is already 12.”可知，他已经12岁了，可以自己去上学了，应填old enough。 18．The baby elephant is not strong ________ to protect itself from dangerous hunters. A．enough B．too C．very D．so 【答案】A 【详解】句意：这只小象不够强壮，无法保护自己免受危险猎人的伤害。 enough足够地；too太；very非常；so如此。enough修饰形容词或副词时需后置，结构为“adj./adv.+enough+to do sth.”。根据“strong…to protect”可知strong是形容词，空缺处应填enough。 19．The girl is ________ to help her classmates with their English studies. A．enough kind B．kind enough C．too kind D．kind too 【答案】B 【详解】句意：这个女孩足够善良去帮助她的同学学习英语。 enough修饰形容词时要后置，结构为“形容词+enough”；too修饰形容词时要前置，结构为“too+形容词”，且too… to…通常表示否定含义“太……而不能……”。根据句意“帮助同学”可知是肯定含义，且enough应放在kind之后。故填kind enough。 20．The man was trustworthy ________ to win the trust of all the people around him. A．too B．enough C．so D．such 【答案】B 【详解】句意：这个人足够可靠，赢得了周围所有人的信任。 too太；enough足够；so如此；such如此。“形容词+enough to do sth.”是固定结构，表示“足够……去做某事”，enough放在形容词trustworthy之后，符合语法和语境。 21．In many countries, people are _________ follow others instead of pushing past them when walking on crowded streets. A．too polite to B．so polite that C．polite enough to D．polite enough that 【答案】C 【详解】句意：在许多国家，当走在拥挤的街道上时，人们足够有礼貌去跟随他人而不是从他们身边挤过去。 too... to...表示否定含义，意为太……而不能……；so... that...后接从句；adj+enough to do表示肯定含义，意为足够……去做某事。根据句意，人们跟随他人是礼貌的行为，且follow为动词原形，符合enough to 结构。 22．The new rule about school manners is _________ understand. Even the new students can follow it easily. A．too clear to B．clear enough to C．too difficult to D．difficult enough 【答案】B 【详解】句意：关于学校礼仪的新规则足够清楚以至于能够理解。甚至新生都能轻易遵守它。 too...to...太……以至于不能……，表否定；adj.+enough to do足够……去做……，表肯定。根据后句“Even the new students can follow it easily.”可知，规则简单易懂，应用“clear enough to understand”结构，表肯定含义。 23．Parents can give advice when needed, but ________ is up to us to decide how to spend our pocket money. A．this B．that C．it D．these 【答案】C 【详解】句意：父母可以在需要的时候给出建议，但是如何支配我们的零花钱由我们自己决定。 考查代词辨析。this这个；that那个；it它；these这些。根据“... is up to us to decide how to spend our pocket money.”可知，此处是“it is up to sb. to do sth.”结构，表示“由某人决定做某事”，其中it作形式主语，真正的主语是动词不定式“to decide how to spend our pocket money”。故选C。 24．________ relaxing for us to spend some time in the countryside on weekends. A．It’s B．That’s C．This is D．There’s 【答案】A 【详解】句意：对我们来说，周末花些时间在乡村度过是令人放松的。 句中真正的主语是动词不定式短语“to spend some time…”，用it作形式主语置于句首，构成“It’s+adj.+for sb.+to do sth.”结构。B、C、D 选项均不能在此句型中作形式主语。故选A。 25．It’s very kind ________ you ________ your free time to look after the sick kids in the hospital. A．of; to spend B．for; to spend C．of; spending D．for; spending 【答案】A 【详解】句意：你真是太好了，在空闲时间照顾医院里生病的孩子。 It is+形容词+for/of sb+to do sth“某人做某事……”，it是形式主语，真正的主语是动词不定式；描述事物的性质时，用for，描述人的品质或性格时，用of，kind“善良”体现人的品质，介词用of。 26．—What do you think is a good way for us students to keep healthy? —It is important ________ students ________ part in outdoor activities. A．for; to taking B．for; to take C．of; to taking D．of; to take 【答案】B 【详解】句意：——你认为我们学生保持健康的好方法是什么？——对学生来说，参加户外活动是很重要的。 固定句型“It is+adj.+for/of sb.+to do sth.”，important描述事情性质，介词用for，若修饰人的品质则用of；动词不定式作真正主语，to后接动词原形。应填for; to take。 27．With the help of the volunteer guide, ________ is easy for the blind people to walk around the park safely. A．that B．it C．them D．this 【答案】B 【详解】句意：在志愿者向导的帮助下，盲人们可以安全地在公园里散步，这很容易。 本句是“It is+adj.+for sb.+to do sth.”的固定句型，意为“对某人来说做某事是……的”。其中，it是形式主语，真正的主语是后面的动词不定式短语“to walk around the park safely”。其他选项均不符合此句型结构。应填it。 28．When you find ________ in front of the Grand Canyon, you’ll find ________ hard to describe its grandeur in words. A．you; it B．you; it’s C．yourself; it D．yourself; itself 【答案】C 【详解】句意：当你发现自己站在大峡谷面前时，你会发现很难用语言描述它的宏伟。 第一空，主语是you，宾语指代主语自身，应用反身代词yourself；第二空，考查固定句型find it+adj.+to do sth.，it作形式宾语，指代后面的动词不定式。 29．It’s not good ________ too much time on online shopping. A．waste B．to waste C．wasting D．wasted 【答案】B 【详解】句意：浪费太多时间在网购上是不好的。 It’s+adj.+to do sth“做某事是……的”，其中It是形式主语，真正的主语是动词不定式，此处填waste“浪费”的不定式形式to waste。 30．________ our duty ________ the classroom clean. A．It’s; keep B．That’s; to keep C．It’s; to keep D．It’s; keeping 【答案】C 【详解】句意：保持教室干净是我们的责任。 根据固定句型“It’s +名词+ to do sth.”可知，it作形式主语，真正的主语是动词不定式to keep。 31．—How generous it is ________ him to give all his pocket money to the poor! —Yes, he is a kind boy. A．for B．of C．to D．with 【答案】B 【详解】句意：——他把所有零花钱都给穷人，他是多么大方啊！——是的，他是个善良的男孩。 for为了；of……的；to到；with和。根据“How generous it is…him to give all his pocket money to the poor!”可知，此处为固定句型“It is+adj+of/for+sb+to do sth”，当形容词表示人的性格、品质时，介词用of。应填of。 32．It ________ ten years since the first generation of Huawei smartwatches ________ on the market. A．was; came B．was; has come C．has been; came D．has been; has come 【答案】C 【详解】句意：自从第一代华为智能手表上市以来，已经十年了。 此处使用句子结构“It be+时间段+since从句”，意为“自从……已经多久了”。主句常用现在完成时has been表示持续到现在的时间，since引导的从句常用一般过去时，came表示过去的起点。 33．It’s meaningful ________ more classic books in our free time. A．read B．to read C．reading D．reads 【答案】B 【详解】句意：在我们的空闲时间多读一些经典书籍是有意义的。 根据“It’s meaningful…more classic books in our free time.”可知，此处为固定句型It’s+adj.+to do sth.，it是形式主语，动词不定式是真正主语。应填to read。 34．________ is necessary for teenagers to learn about nature and the environment. A．This B．That C．It D．What 【答案】C 【详解】句意：青少年了解自然和环境是必要的。 “It is+adj+for sb+to do sth”意为“做某事对某人来说是……的”，其中It作形式主语，真正的主语是后面的动词不定式。 35．It’s rude ________ laugh at others when they make mistakes. A．of you to B．for you to C．of you D．for you 【答案】A 【详解】句意：当别人犯错时嘲笑他们，你真是太粗鲁了。 此处使用句型It’s+adj.+of/for sb.+to do sth.。形容词rude“粗鲁的”表示人的品质特征，介词使用of；不定式作真正主语，to不可省略。 36．—Jack was too nervous to ________ himself ________. —Exactly, he didn’t have ________. A．explain; enough clearly; enough confidence B．express; clearly enough; enough confidence C．explain; clearly enough; confidence enough D．express; enough clearly; confidence enough 【答案】B 【详解】句意：——杰克太紧张了，以至于不能清楚地表达自己。——确实，他没有足够的自信。 explain解释；express表达。第一空：“express oneself”为固定搭配，意为“表达自己”，explain后通常接具体内容，不接反身代词。第二空：修饰动词express应用副词clearly，enough修饰形容词或副词时应后置，即clearly enough。第三空：confidence为不可数名词，enough修饰名词时应前置，即enough confidence。 37．The boy is only 7 years old. He isn’t ________ to take care of ________. A．old enough; himself B．enough old; himself C．old enough; him D．enough old; him 【答案】A 【详解】句意：这个男孩只有7岁。他还不够大，不能照顾自己。 old是形容词，enough修饰形容词时需后置，即放在形容词之后；当动词短语的宾语与主语指代同一人时，需使用反身代词himself。 38．Because of AI tools like DeepSeek, ________ is possible for us to find out many answers without using search engines. A．that B．it C．them D．this 【答案】B 【详解】句意：得益于像DeepSeek这样的人工智能工具，我们无需使用搜索引擎就能找到很多答案。 考查代词用法。It is+adj.+for sb. to do sth.为固定句型，其中it作形式主语，真正的主语是后面的不定式短语。故选B。 39．________ is wrong of us ________ products made from animals in danger, and ________ is our duty ________ them. A．It; to buy; it; to protect B．It; buying; that; protecting C．That; to buy; it; to protect D．That; buying; that; protecting 【答案】A 【详解】句意：我们购买濒危动物制品是错误的，并且保护它们是我们的责任。 It它；That那。固定句型It is+形容词+of sb+to do sth“某人做某事是……的”，It作形式主语，真正的主语是动词不定式，故第一空填It，第二空填to buy；后半句符合结构It is one’s duty to do sth“做某事是某人的责任”，同样用it作形式主语，真正主语是不定式to protect。 40．We all thought ________ necessary for you to spend as much time as you could ________ English. A．that; improving B．it is; to improve C．it; improve D．it was; improving 【答案】D 【详解】句意：我们都认为你尽可能多地花时间提高英语是必要的。 考查it作形式宾语及固定搭配。第一空，根据“We all thought…necessary for you to…”可知，此处表示我们都认为你尽可能多地花时间提高英语是必要的，应用it作形式宾语，结构为“主语+动词+it+for sb. to do sth.”，真正的宾语是动词不定式，此处也可理解为thought (过去式) 后是省略了that的宾语从句，宾语从句的句子结构是“It+is/was+for sb. to do sth.”，主句是一般过去时，故宾语从句中be动词应用was；第二空，“spend time (in) doing sth.”为固定搭配，表示“花费时间做某事”。故选D。 10 同步新教材，周周有练习，月月有重点！ 11 同步新教材，周周有练习，月月有重点！ 学科网（北京）股份有限公司 $