Unit 5 Saving animals in danger 形式主语it和enough to do（单元核心语法精练）英语新教材沪教版八年级下册

Unit 5 Saving animals in danger 核心语法精练（形式主语it和enough to do） 目录 A 考点概览·知识回顾 1 B 考点夯基·专项突破 2 一、选择题 2 二、用括号内动词的正确形式填空 5 三、完成句子 6 C 综合攻坚·能力跃升 9 题型一 语法选择 9 题型二 语法填空 9 形式主语it 当动词不定式to do在句子中作主语时，为了保持句子平衡，避免头重脚轻，常用it作形式主语。it作形式主语时没有词义。常见句型如下： It is + 形容词 + for sb. to do sth. 对于某人来说，……是……的 （当形容词修饰动词或动词短语时，介词用for，如important, easy, difficult, necessary, dangerous, interesting, possible等） It is important for us to protect nature. 对于我们来说，保护大自然是重要的。 It is not easy for many species to survive. 对于很多物种来说，生存并不容易。 It is + 形容词 + of sb. to do sth. 某人做某事是……的 （当形容词修饰人物特征或品质时，介词用of，如kind， cruel, wrong, right, helpful, clever, foolish, polite, careful, wise等） It is cruel of them to kill animals in danger. 他们杀害濒危动物是残忍的。 It is kind of them to help! 他们来帮忙是很善良的。 It takes sb. some time to do sth. 某人花费某些时间去做某事 It took me three days to finish the work. 我花费了3天时间去完成这项工作。 形容词 / 副词 + enough to do sth. 形容词 + enough to do sth. 表示 “足够……去做某事” The elephant is strong enough to walk. 这大象足够强壮去行走。 否定形式为 not + 形容词 + enough t do，可与too...to...互换 The elephant is not strong enough to walk. = The elephant is too weak to walk. 这大象不足够强壮去行走。 副词 + enough to do sth. 表示 “足够……去做某事” She sings well enough to win the competition. 她唱得足够好，赢得了比赛。 一、选择题 1. ________ is necessary for us to learn to be independent from a young age. A. That B. This C. It D. One 【答案】C 【详解】句意：对我们来说，从小学习独立是必要的。 考查it作形式主语的用法。That那个；This这个；It它；One一个。本句中，真正的主语是动词不定式短语to learn to be independent from a young age，而空缺处需要填入一个形式主语，在英语中通常用it来充当形式主语。故选C。 2. It’s important ________ a good learning habit. A. to develop B. develop C. developing D. developed 【答案】A 【详解】句意：培养良好的学习习惯很重要。 It’s+adj.+to do sth“做某事是……的”，It是形式主语，动词不定式是真正主语，此处填“培养”的不定式形式 to develop。 3. It’s necessary ________ us ________ exercise every day. A. for; to do B. of; to do C. for; doing D. of; doing 【答案】A 【详解】句意：对我们来说，每天锻炼是必要的。 考查固定句型“It’s + adj. + for sb. + to do sth.”，表示“对某人来说做某事是……”。necessary属于描述事物性质的形容词，通常用for sb.；且it作形式主语时，真正的主语用不定式to do。故选A。 4. It is interesting for students ________ part in the school’s Arts and Sports Festival. A. takes B. taking C. to take D. will take 【答案】C 【详解】句意：学生们参加学校的艺术体育节是很有趣的。 考查非谓语动词。根据“It is interesting for students…part in the school’s Arts”可知，此处是“It is+形容词 +for sb. to do sth.”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to do sth.。因此空格处应填动词不定式to take。take part in是固定短语，意为“参加”。故选C。 5. What a long way ________ is from Nanjing to London! A. this B. it C. that D. / 【答案】B 【详解】句意：从南京到伦敦是多么长的一段路程啊！ 考查代词辨析。this这个，常用来指代较近的人或事物；it可作形式主语或形式宾语等，在此句中作形式主语，真正的主语是后面的“from Nanjing to London”；that那个，常用来指代较远的人或事物；“/”表示不填。在“What a long way...is from Nanjing to London!”这个感叹句结构中，真正的主语是“a long way”这个距离，为了避免句子头重脚轻，用it作形式主语。故选B。 6. It ______ a lot of money and time to build the Great Wall in ancient times. A. cost B. took C. spent D. paid 【答案】B 【详解】句意：在古代，修建长城花费了大量的金钱和时间。 考查动词辨析。cost花费，主语为物，sth. cost sb. money某物花费某人金钱；took花费，主语为it，it took money to do sth.做某事花费时间或金钱；spent花费，sb.spent money doing sth.某人花费时间或金钱；paid支付，主语为人，常与for搭配。根据“It...a lot of money and time to build the Great Wall in ancient times.”可知，主语是“it”，形式主语，指代“to build the Great Wall”，符合句意。故选B。 7. Usually, ________ is difficult ________ a boy of five years old to dress himself. A. that; for B. that; of C. it; for D. it; of 【答案】C 【详解】句意：通常，对于一个五岁的男孩来说，自己穿衣服是困难的。 考查it作形式主语以及介词辨析。that那个；it它；for对于；of……的。根据“... is difficult ... a boy of five years old to dress himself.”可知，此处使用it作形式主语，构成“it is+adj.+for sb. to do sth.”句型，表示“对于某人来说，做某事是……的”，所以第一空用it，第二空用for。故选C。 8. —How dangerous it is ________ the kids ________ the kite in the street!     —Let’s stop them right now. A. for; to fly B. of; flying C. of; to fly D. for; flying 【答案】A 【详解】句意：——孩子们在街上放风筝是多么危险啊！——让我们马上制止他们吧。 for为了；of……的。“It is+adj+for/of sb+to do sth”是句型，该句型中真正的主语是动词不定式，因此第二空应填to fly，排除B、D；介词选择取决于形容词，若形容词描述人的品质（如kind, clever）用of，若描述事情性质（如dangerous, hard）用for。此处dangerous描述放风筝这件事的危险性，故第一空填for。 9. —It’s nice ________ you ________ bad words about others.             —Thank you. That’s what I should do. A. of; to say B. for; to say C. of; not to say D. for; not to say 【答案】C 【详解】句意：——你不说别人的坏话真好。——谢谢。那是我应该做的。 此处是“It’s + adj. + of/for sb. to do sth.”结构，形容词nice描述的是人的品质（友善、善良），应用介词of；结合语境“That’s what I should do.”可知，对方是在表达感谢，说明说话内容是不说坏话，因此不定式应为否定形式not to say。故选C。 10. —It was very honest ________ you to return the wallet you found with all the money inside. —Thanks. I just think it’s important ________ us to do the right thing. A. of; for B. for; to C. of; to D. for; of 【答案】A 【详解】句意：——你把捡到的钱包归还回去，而且里面的钱也都还了，这真是太诚实了。——谢谢。我只是觉得对我们来说，做正确的事是很重要的。 句型“It is+形容词+of/for sb to do sth”来表示“某人做某事怎么样”，在这个句型中，如果形容词是描述人的性格、品质的，用介词“of”，如果形容词是描述事情的则用介词“for”。第一空，“honest”意思是“诚实的”，是描述人的品质的形容词，所以第一空应该用“of”；第二空，“important”意思是“重要的”，是描述事情的形容词，所以第二空应该用“for”。 二、用括号内动词的正确形式填空 1. It’s difficult for my little sister _________ (solve) this maths problem. 【答案】to solve 【详解】句意：解决这个数学问题对于我妹妹来说是困难的。根据提示可知，此处考查it is adj. for sb to do sth.“做某事对于某人来说是……”。用不定式to solve作真正主语。 2. It’s useful for us ________ (learn) something about great inventions. 【答案】to learn 【详解】句意：了解一些伟大的发明对我们很有帮助。根据题意和提示词可知，It’s+形容词+for sb. to do sth.意为“做某事对于某人是……的”，It是形式主语，动词不定式to do做真正的主语，所以，此处应填learn的不定式形式。故填to learn。 3. It’s a good idea ________ (join) the English club to improve your language skills. 【答案】to join 【详解】句意：加入英语俱乐部是个好主意，可以提高你的语言技能。It + be + 名词/形容词 + to do sth“做某事是……”，该结构中It是形式主语，真正的主语是动词不定式，因此括号内的动词join要变为不定式形式to join。故填to join。 4. It’s not easy ________ (learn) to live with nature. 【答案】to learn 【详解】句意：学会与自然共处并不容易。根据“It’s not easy...”可知此处需填入动词不定式形式，作句中真正的主语，构成句型“It + be + 形容词 + to do sth”，提示词learn需要变为不定式形式。故填to learn。 5. It takes me about two hours _________ (do) some shopping. 【答案】to do 【详解】句意：购物花了我大约两个小时。该题考查固定句型“it takes sb. some time to do sth.”, 意为“做某事花费了某人多长时间”，其中it为形式主语，不定式to do sth.为真正的主语。句子所给词为do，空格处应填do的不定式形式。故填to do。 6. What great fun it is _________ (see) the elephants take bananas from the visitors! 【答案】to see 【详解】句意：看到大象从游客手中拿走香蕉是多么有趣啊。see“看到，看见”，动词。根据“it is...the elephants take...”可知，该句使用了句型：It is +n./adj. to do sth“做某事是……”。故填to see。 7. The ________ of the river here is about 5 metres, and it’s ________ enough for swimming. (deep) 【答案】 depth deep 【详解】句意：这里这条河的深度大约是5米，足够深可以游泳。deep“深的”，形容词；第一空The后接名词depth表示深度，第二空be动词后接形容词deep作表语。故填depth；deep。 8. Lucy is ________ (confidence) enough to make a speech in front of the class. 【答案】confident 【详解】句意：露西足够自信，可以在全班同学面前做演讲。confidence“信心”，名词。此处需要形容词作表语，confidence的形容词形式是confident“自信的”。故填confident。 9. The water in the river is ________ enough to see the fish. (clearly) 【答案】clear 【详解】句意：河里的水足够清澈，能看到鱼。根据“The water in the river is…enough to see the fish.”可知，这里需要一个形容词作表语，clear“清澈的”符合语境，enough修饰形容词需后置，说明水的状态能让人看到鱼。故填clear。 10. She is ________ (brave) enough to help the lost boy find his mother in the street. 【答案】 brave 【详解】句意：她足够勇敢，在街上帮助迷路的男孩找到了他的妈妈。 be动词后接形容词原级，brave“勇敢的”符合语境。故填brave。 11. She feels tired because she didn’t get enough ________ (sleep) last night. 【答案】 sleep 【详解】句意：她感到疲倦，因为她昨晚没睡够。enough后接名词；根据括号内单词提示可知，此处用sleep，表示“睡眠”，是名词。故填sleep。 12. I have enough ________ (confident) to solve this problem. 【答案】confidence 【详解】句意：我有足够的信心解决这个问题。enough为形容词，后需接名词作宾语，所给词confident的名词形式为confidence，意为“信心”。 三、完成句子 1. 充足的睡眠能帮助我们更好地学习。 Enough ________ can help us study ________. 【答案】sleep better 【详解】根据中英文对照可知，此处缺少“睡眠”和“更好地”。sleep“睡眠”，不可数名词。better“更好地”，副词，修饰动词“study”。故填sleep；better。 2. 他足够勇敢去面对困难。 He is ________ ________ to face difficulties. 【答案】brave enough 【详解】原句中“足够勇敢”是关键词，表示“足够”的英文是enough；表示“勇敢”的英文是brave。enough修饰形容词时，需放在形容词的后面。故填brave；enough。 3. 帮助有需要的人对我们来说很有意义。 ________ ________ for us to help people in need. 【答案】It’s meaningful 【详解】根据中英文对照可知，此处缺少“很有意义”。本句为固定句型“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为形式主语，真正的主语是后面的不定式短语“to help people in need”。“很有意义”用形容词meaningful表达。故填It’s；meaningful。 4. 这片湿地不够大，容不下这么多鸟生活。 The wetland is not ________ ________ for so many birds to live in. 【答案】 large enough 【详解】原句中“不够大”是关键词组，其中“大”对应的英文单词是“large”，“不够……来做某事”常用结构“not+形容词+enough+to do sth.”来表达。所以这里要填“large enough”，表示“不够大”。 5. 在许多亚洲国家，人们用筷子吃饭是很常见的。 In many Asian countries, ________ ________ for people to eat with chopsticks. 【答案】 it’s common 【详解】根据中英文对照可知，此处缺少“是很常见的”。“对某人来说做某事是……的”用固定句型“It be + adj. + for sb. to do sth.”表达，本句描述持续的认知，时态为一般现在时，be动词用is，it is缩写为it’s；“常见的”用形容词common表达，在句中作表语。故填it’s；common。 6. 这个男孩足够强壮，可以举起这个重箱子。 The boy is ________ ________ ________ lift the heavy box. 【答案】 strong enough to 【详解】根据中英文对照可知，此处缺“足够强壮可以……”。strong“强壮的”，在句中作表语，enough“足够地”，副词，修饰形容词时要放在形容词后面，后跟动词不定式。“形容词+enough+to do sth”表示“足够……做某事”。故填strong；enough；to。 7. 这个椅子不够高，我够不到黑板顶部。 This chair isn’t ______ ______ for me to reach the top of the blackboard. 【答案】 tall enough 【详解】原句中“够高”是关键词，“足够的”英文单词是enough，“高的”英文单词是tall，是形容词，在句中作表语，enough修饰形容词，位于形容词后，故填tall；enough。 8. 她足够细心，注意到了地上的碎玻璃。 She was _________ _________ to _________ the broken glass on the ground. 【答案】careful enough notice 【详解】根据中英文对照可知，此处缺“足够细心”和“注意到”。“足够细心”对应的英语是“careful enough”，“注意到”是“notice”，且“be+形容词+enough to do sth”是固定结构，故填careful；enough；notice。 9. 对我们来说，每天充分利用时间是很重要的。 It’s ________ for us ________ make ________ ________ ________ time ________ ________. 【答案】 important to full use of every day 【详解】原句中的“重要的”，“充分利用”和“每天”是关键词。表示“重要的”的单词为important，用于“It’s important for sb to do sth”结构，表示“做某事对某人来说是很重要的”；表示“充分利用”的短语为make full use of；表示“每天”的短语为every day，放句尾作时间状语。 10. 出门旅行时带一些现金很方便。 It is convenient ________ ________ some cash when traveling. 【答案】to carry 【详解】原句中“带”是关键词，表示“带”的单词是carry，本句为it作形式主语的固定句型，用动词不定式作真正的主语，即to+动词原形。 题型一 语法选择 （2025广州华师附中期中）The giraffe（长颈鹿）is the tallest animal on land. Their interesting shapes attract 1 people to visit them. They have long necks and long thin legs. Their front legs are 2 than their back legs. Some of 3 can be more than five meters tall. They can run very fast—about 30 miles 4 hour. They are usually brown and yellow. Giraffes live 5 Africa. They 6 live up to 25 years in the wild. They spend most of the day 7 . The leaves, flowers and fruit are their main food, and they also eat grass or 8 plants. To find food, they travel over a large area, 9 they don’t have a fixed（固定的）home. However, when a mother giraffe gives birth to babies, it often returns to 10 birthplace. It only gives birth to one baby every time, and the baby giraffe is cute and can be 11 . About 20 minutes after being born, the baby giraffe learns to stand. Then it begins drinking 12 milk from its mother. A few hours later, it can run as 13 as those who have been born for weeks. 14 amazing! The baby giraffe only stays with its mother after it is born in the first two weeks. When it is strong enough, it 15 its mother and start a new life. 1. A. thousand of B. thousand C. thousands of D. thousands 2. A. long B. longer C. longest D. the longest 3. A. they B. them C. their D. theirs 4. A. a B. an C. the D. / 5. A. in B. at C. on D. to 6. A. need B. should C. must D. can 7. A. eating B. ate C. eat D. to eat 8. A. others B. another C. other D. the others 9. A. until B. but C. therefore D. so 10. A. it B. it’s C. its D. itself 11. A. 1.8 meter tall B. 1.8 meters tall C. 1.8-meter-tall D. 1.8-meters-tall 12. A. some B. any C. no D. none 13. A. quick B. quickly C. more quickly D. most quickly 14. A. What a B. What an C. How D. How an 15. A. leaves B. left C. is leaving D. will leave 【答案】1. C 2. B 3. B 4. B 5. A 6. D 7. A 8. C 9. D 10. C 11. B 12. A 13. B 14. C 15. D 【导语】本文是一篇说明文，介绍的是长颈鹿，包括其体型、运动能力、生活习性、生育和出生等。 1. 句意：它们有趣的形状吸引了成千上万的人前来参观。 thousand of没有此表达；thousand千，当与具体数字连用时，通常不加复数词尾-s，其后不接介词of；thousands of成千上万的，后接名词，表示不确定的数；thousands数千（thousand的复数形式）。观察句子结构可知，空格前没有具体数字，本题考查thousands of表示不确定的数。故选C。 2. 句意：它们的前腿比后腿长。 long长的；longer更长的（long的比较级）；longest最长的（long的最高级）；the longest最长的。根据空格后的标志词“than”可知，空格上要用比较级，故选B。 3. 句意：其中一些可能超过五米高。 they它们，主格代词；them它们，宾格代词；their它们的，形容词性物主代词；theirs它们的，名词性物主代词。根据空格前的介词“of”以及提供的选项可知，空格上填代词宾格形式，故选B。 4. 句意：它们跑得很快——大约每小时30英里。 a表示数量“一”，用在读音以辅音音素开头的单数可数名词前；an表示数量“一”，用在读音以元音音素开头的单数可数名词前；the表示特指。根据句意可知，这里考查的是冠词的用法，表示“每”，因为空格后的单词“hour”的读音是以元音音素开头的单数可数名词，应该用冠词an，故选B。 5. 句意：长颈鹿生活在非洲。 in在……里面；at在；on在……上；to到。根据句意可知，本题考查“live in + 大地点”，故选A。 6. 句意：它们在野外可以活25年。 need需要；should应该；must必须；can能。根据句意可知，句子表达的意思是“长颈鹿在野外可以活25年”，考查情态动词can，故选D。 7. 句意：它们一天的大部分时间都在吃东西。 eating吃（eat的动名词形式或现在分词形式）；ate吃（eat的过去式）；eat吃（动词原形）；to eat吃（eat的动词不定式形式）。根据句意可知，本题考查“spend + 时间 + (in) doing sth花费时间做某事”，故空格上填动名词形式，故选A。 8. 句意：树叶、花朵是它们的主要食物，同时它们也吃草或其他植物。 others其他的人或物，代词；another另一个（指三者或者三者以上中的另一个）；other其他的，形容词修饰名词的复数；the others相当于“the other + 复数可数名词”。根据空格后的名词复数形式可知，空格上应填形容词，故选C。 9. 句意：为了寻找食物，它们要穿越一片很大的区域，因此，它们没有固定的家。 until直到；but但是；therefore因此（后面要用逗号隔开）；so因此。观察空格前的句子“To find food, they travel over a large area”以及空格后的句子“they don’t have a fixed（固定的） home.”可知，空格前后的句子是因果关系，再结合空格后没有逗号隔开，故选D。 10. 句意：然而，当一只长颈鹿妈妈要生宝宝时，它经常回到它的出生地。 it它，代词；it’s它是；its它的，形容词性物主代词；itself它自己，反身代词。根据句意可知，空格处要填形容词物主代词；根据句子的主语“it”可知，“it”对应的形容词性物主代词是its，故选C。 11. 句意：它每次只生一只长颈鹿，而且长颈鹿宝宝很可爱，可能是1.8米高。 1.8 meter tall没有此表达；1.8 meters tall 1.8米高；1.8-meter-tall 1.8米高的，带有形容词功能；1.8-meters-tall没有此表达。本空考查身高的表达形式：基数词+单位名词复数形式+tall，故选B。 12. 句意：然后，它开始喝妈妈的奶。 some一些，可修饰可数名词或不可数名词，一般用于肯定句；any任何一个，任何的，可修饰可数名词或不可数名词，一般用于否定句或疑问句；no没有；none表示在3个或3个以上中没有一个。根据后文的语境“A few hours later, it can run and has no difference with those who have been born for weeks.”可知，小长颈鹿应该是喝一些妈妈的奶，故选A。 13. 句意：几个小时后，它可以跑得像那些出生了几周的长颈鹿一样快。 quick快的；quickly快地；more quickly更快地；most quickly最快地。结合该句中的as...as可知考查同级比较，且谓语动词can run是实义动词，故该空要填一个副词，故选B。 14. 句意：太神奇了！ 感叹句的结构：What a/an + 形容词+可数名词单数+主语+谓语+其它；how+形容词/副词+主语+谓语+其它。观察句子结构可知，本句省略了主语和谓语，主语前是形容词“amazing”，符合“how+形容词/副词+主语+谓语+其它”，故选C。 15. 句意：当它足够强壮时，它会离开母亲，开始新的生活。 leaves离开（leave的三单形式）；left离开（leave的过去式）；is leaving离开（现在进行时）；will leave将要离开（一般将来时）。本句是when引导的时间从句，符合“主将从现”。空格所在句为主句，时态应该是一般将来时。故选D。 题型二 语法填空 阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。将答案填写在答题卷的相应位置。 （2023深圳福田区期末）Flamingos (火烈鸟) are one of the most beautiful birds in the world. At 1 (born), they are grey or white. And they slowly turn pink when they grow up. They can usually live 20 to 30 years, and some even live up to the age of 50. They are able to “run” on the water because of their special 2 (foot). Dr Paul Rose and his team have done a study on flamingos. It shows the birds always live in large groups, but they spend most of the time with a small group of friends, just 3 people. “It’s easy to find out whether flamingos are friends or not. Usually, 4 group of friends sit or stand less than one neck length away from each other. So when other groups of flamingos come too near, they will extend(伸长) their long necks 5 (fight),” Dr Rose said. Another interesting thing 6 (find) by the team and it surprised them—Flamingos choose those with similar personalities and colours when making friends. The findings of the study are important 7 they can help zoos get to know how to keep flamingos happy and 8 (health). “Keepers should have as many birds as possible. If the group is bigger, the flamingos will be able to find their friends 9 (easy),” Dr Rose said. “And when moving 10 (they) from one zoo to another, keepers should be careful not to keep the birds away from their good friends.” 【答案】1．birth 2．feet 3．like 4．a 5．to fight 6．was found 7．because 8．healthy 9．easily 10．them 【导语】本文介绍了有关火烈鸟的相关研究。 1．句意：出生时，它们是灰色或白色的。此处是短语at birth“出生时”，故填birth。 2．句意：它们能够在水上“奔跑”是因为它们的脚很特别。根据“their”可知，名词应用复数形式，故填feet。 3．句意：这表明鸟类总是成群生活，但它们大部分时间都和一小群朋友在一起，就像人一样。根据“they spend most of the time with a small group of friends, just...people”可知，此处指的是“就像人一样”，just like“就像”，故填like。 4．句意：通常情况下，一群朋友坐着或站着时距离彼此不到一个脖子的长度。根据“group of friends sit or stand less than one neck length away from each other.”可知，此处说的是“一群朋友”，a“一个”，故填a。 5．句意：所以当其他火烈鸟群离得太近时，它们会伸出长脖子来战斗。空处表示目的，应用不定式作目的状语，故填to fight。 6．句意：研究小组发现了另一件有趣的事情。空处修饰句子主语“Another interesting thing”，此处表示“有趣的事情被发现”，根据and后“it surprised them”，可知用一般过去时的被动语态，结构为was/were done，主语为名词单数，系动词用was。故填was found。 7．句意：这项研究的发现很重要，因为它们可以帮助动物园了解如何让火烈鸟保持快乐和健康。空格前后是因果关系，后句表示原因，应用because引导原因状语从句，故填because。 8．句意：这项研究的发现很重要，因为它们可以帮助动物园了解如何让火烈鸟保持快乐和健康。and连接并列成分，空处与“happy”构成并列关系，此处应用形容词形式，故填healthy。 9．句意：如果这个群体更大，火烈鸟就能很容易地找到它们的朋友。空处修饰句中的动词，应用副词形式，故填easily。 10．句意：当把它们从一个动物园转移到另一个动物园时，饲养员应该小心，不要让它们远离它们的好朋友。空处作宾语，应用宾格形式，故填them。 1 / 12 学科网（北京）股份有限公司 $ Unit 5 Saving animals in danger 核心语法精练（形式主语it和enough to do） 目录 A 考点概览·知识回顾 1 B 考点夯基·专项突破 2 一、选择题 2 二、用括号内动词的正确形式填空 5 三、完成句子 6 C 综合攻坚·能力跃升 4 题型一 语法选择 4 题型二 语法填空 4 形式主语it 当动词不定式to do在句子中作主语时，为了保持句子平衡，避免头重脚轻，常用it作形式主语。it作形式主语时没有词义。常见句型如下： It is + 形容词 + for sb. to do sth. 对于某人来说，……是……的 （当形容词修饰动词或动词短语时，介词用for，如important, easy, difficult, necessary, dangerous, interesting, possible等） It is important for us to protect nature. 对于我们来说，保护大自然是重要的。 It is not easy for many species to survive. 对于很多物种来说，生存并不容易。 It is + 形容词 + of sb. to do sth. 某人做某事是……的 （当形容词修饰人物特征或品质时，介词用of，如kind， cruel, wrong, right, helpful, clever, foolish, polite, careful, wise等） It is cruel of them to kill animals in danger. 他们杀害濒危动物是残忍的。 It is kind of them to help! 他们来帮忙是很善良的。 It takes sb. some time to do sth. 某人花费某些时间去做某事 It took me three days to finish the work. 我花费了3天时间去完成这项工作。 形容词 / 副词 + enough to do sth. 形容词 + enough to do sth. 表示 “足够……去做某事” The elephant is strong enough to walk. 这大象足够强壮去行走。 否定形式为 not + 形容词 + enough t do，可与too...to...互换 The elephant is not strong enough to walk. = The elephant is too weak to walk. 这大象不足够强壮去行走。 副词 + enough to do sth. 表示 “足够……去做某事” She sings well enough to win the competition. 她唱得足够好，赢得了比赛。 一、选择题 1. ________ is necessary for us to learn to be independent from a young age. A. That B. This C. It D. One 2. It’s important ________ a good learning habit. A. to develop B. develop C. developing D. developed 3. It’s necessary ________ us ________ exercise every day. A. for; to do B. of; to do C. for; doing D. of; doing 4. It is interesting for students ________ part in the school’s Arts and Sports Festival. A. takes B. taking C. to take D. will take 5. What a long way ________ is from Nanjing to London! A. this B. it C. that D. / 6. It ______ a lot of money and time to build the Great Wall in ancient times. A. cost B. took C. spent D. paid 7. Usually, ________ is difficult ________ a boy of five years old to dress himself. A. that; for B. that; of C. it; for D. it; of 8. —How dangerous it is ________ the kids ________ the kite in the street!     —Let’s stop them right now. A. for; to fly B. of; flying C. of; to fly D. for; flying 9. —It’s nice ________ you ________ bad words about others.             —Thank you. That’s what I should do. A. of; to say B. for; to say C. of; not to say D. for; not to say 10. —It was very honest ________ you to return the wallet you found with all the money inside. —Thanks. I just think it’s important ________ us to do the right thing. A. of; for B. for; to C. of; to D. for; of 二、用括号内动词的正确形式填空 1. It’s difficult for my little sister _________ (solve) this maths problem. 2. It’s useful for us ________ (learn) something about great inventions. 3. It’s a good idea ________ (join) the English club to improve your language skills. 4. It’s not easy ________ (learn) to live with nature. 5. It takes me about two hours _________ (do) some shopping. 6. What great fun it is _________ (see) the elephants take bananas from the visitors! 7. The ________ of the river here is about 5 metres, and it’s ________ enough for swimming. (deep) 8. Lucy is ________ (confidence) enough to make a speech in front of the class. 9. The water in the river is ________ enough to see the fish. (clearly) 10. She is ________ (brave) enough to help the lost boy find his mother in the street. 11. She feels tired because she didn’t get enough ________ (sleep) last night. 12. I have enough ________ (confident) to solve this problem. 三、完成句子 1. 充足的睡眠能帮助我们更好地学习。 Enough ________ can help us study ________. 2. 他足够勇敢去面对困难。 He is ________ ________ to face difficulties. 3. 帮助有需要的人对我们来说很有意义。 ________ ________ for us to help people in need. 4. 这片湿地不够大，容不下这么多鸟生活。 The wetland is not ________ ________ for so many birds to live in. 5. 在许多亚洲国家，人们用筷子吃饭是很常见的。 In many Asian countries, ________ ________ for people to eat with chopsticks. 6. 这个男孩足够强壮，可以举起这个重箱子。 The boy is ________ ________ ________ lift the heavy box. 7. 这个椅子不够高，我够不到黑板顶部。 This chair isn’t ______ ______ for me to reach the top of the blackboard. 8. 她足够细心，注意到了地上的碎玻璃。 She was _________ _________ to _________ the broken glass on the ground. 9. 对我们来说，每天充分利用时间是很重要的。 It’s ________ for us ________ make ________ ________ ________ time ________ ________. 10. 出门旅行时带一些现金很方便。 It is convenient ________ ________ some cash when traveling. 题型一 语法选择 （2025广州华师附中期中）The giraffe（长颈鹿）is the tallest animal on land. Their interesting shapes attract 1 people to visit them. They have long necks and long thin legs. Their front legs are 2 than their back legs. Some of 3 can be more than five meters tall. They can run very fast—about 30 miles 4 hour. They are usually brown and yellow. Giraffes live 5 Africa. They 6 live up to 25 years in the wild. They spend most of the day 7 . The leaves, flowers and fruit are their main food, and they also eat grass or 8 plants. To find food, they travel over a large area, 9 they don’t have a fixed（固定的）home. However, when a mother giraffe gives birth to babies, it often returns to 10 birthplace. It only gives birth to one baby every time, and the baby giraffe is cute and can be 11 . About 20 minutes after being born, the baby giraffe learns to stand. Then it begins drinking 12 milk from its mother. A few hours later, it can run as 13 as those who have been born for weeks. 14 amazing! The baby giraffe only stays with its mother after it is born in the first two weeks. When it is strong enough, it 15 its mother and start a new life. 1. A. thousand of B. thousand C. thousands of D. thousands 2. A. long B. longer C. longest D. the longest 3. A. they B. them C. their D. theirs 4. A. a B. an C. the D. / 5. A. in B. at C. on D. to 6. A. need B. should C. must D. can 7. A. eating B. ate C. eat D. to eat 8. A. others B. another C. other D. the others 9. A. until B. but C. therefore D. so 10. A. it B. it’s C. its D. itself 11. A. 1.8 meter tall B. 1.8 meters tall C. 1.8-meter-tall D. 1.8-meters-tall 12. A. some B. any C. no D. none 13. A. quick B. quickly C. more quickly D. most quickly 14. A. What a B. What an C. How D. How an 15. A. leaves B. left C. is leaving D. will leave 题型二 语法填空 阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。将答案填写在答题卷的相应位置。 （2023深圳福田区期末）Flamingos (火烈鸟) are one of the most beautiful birds in the world. At 1 (born), they are grey or white. And they slowly turn pink when they grow up. They can usually live 20 to 30 years, and some even live up to the age of 50. They are able to “run” on the water because of their special 2 (foot). Dr Paul Rose and his team have done a study on flamingos. It shows the birds always live in large groups, but they spend most of the time with a small group of friends, just 3 people. “It’s easy to find out whether flamingos are friends or not. Usually, 4 group of friends sit or stand less than one neck length away from each other. So when other groups of flamingos come too near, they will extend(伸长) their long necks 5 (fight),” Dr Rose said. Another interesting thing 6 (find) by the team and it surprised them—Flamingos choose those with similar personalities and colours when making friends. The findings of the study are important 7 they can help zoos get to know how to keep flamingos happy and 8 (health). “Keepers should have as many birds as possible. If the group is bigger, the flamingos will be able to find their friends 9 (easy),” Dr Rose said. “And when moving 10 (they) from one zoo to another, keepers should be careful not to keep the birds away from their good friends.” 1 / 12 学科网（北京）股份有限公司 $