Unit5语法讲解及习题_形式主语it与“形容词+enough+to+动词” 2025-2026学年沪教版八年级英语下册

沪教（牛津）英语八下Unit5语法讲解及习题 形式主语it与“形容词+enough+to+动词” 一、语法概念 本单元重点学习形式主语it的用法（用于避免主语过长）和“形容词+enough+to+动词”结构（表示“足够……去做某事”），是描述动物保护、能力状态的常用语法。 二、详细用法讲解 1. 形式主语it的用法 当句子的主语是较长的不定式短语时，通常用“it”作形式主语，将真正的主语（不定式短语）放在句末，使句子更简洁平衡。 核心结构 It + be + 形容词 + for sb. + to do sth. （形容词修饰动作，说明“做某事对某人来说是……的”） 例：It is important for us to protect nature.（保护自然对我们来说很重要。） It + be + 形容词 + of sb. + to do sth. （形容词描述人的品质，说明“某人做某事是……的”） 例：It was very kind of him to help!（他帮忙真是太善良了。） 2. “形容词+enough+to+动词”结构 表示“某人/某物具备足够的某种特质，可以完成某个动作”，否定形式可转换为“too+反义词+to+动词”。 核心结构 肯定：主语 + be + 形容词 + enough + to + 动词原形 例：The elephant is now strong enough to walk.（这头大象现在足够强壮，可以走路了。） 否定转换：主语 + be + too + 形容词反义词 + to + 动词原形 例：The elephant was not strong enough to walk. = The elephant was too weak to walk.（这头大象不够强壮，走不了路。） 三、习题训练 （一）用“for”或“of”填空 1. It is necessary ___________ us to protect animals’ homes. 2. It was cruel ___________ the hunters to kill the tiger. 3. It is important ___________ people to learn about endangered animals. 4. It is kind ___________ your uncle to drive you to the event. 5. It is wrong ___________ them to sell products made from endangered animals. 6. It is helpful ___________ students to join environmental groups. 7. It was brave ___________ her to stop the boy from throwing rocks. 8. It is necessary ___________ everyone to follow the wildlife protection rules. 9. It is selfish ___________ some people to destroy animal habitats. 10. It is useful ___________ us to know how to help injured animals. （二）用“形容词+enough+to+动词”完成句子 1. The baby panda is ___________ (not / big / eat) bamboo alone. 2. We are ___________ (old / help) protect endangered animals. 3. The elephant was ___________ (weak / walk) after being injured. 4. The volunteer is ___________ (patient / take care of) the injured wild duck. 5. The bird is ___________ (not / strong / fly) long distances. 6. We are ___________ (smart / find) ways to save animals in danger. 7. The little girl was ___________ (not / tall / reach) the bird’s nest. 8. The zookeeper is ___________ (experienced / deal with) animal emergencies. 9. The river is ___________ (not / clean / drink) for the animals. 10. We are ___________ (energetic / collect) money for the wildlife charity. （三）选择正确的选项 1. ___________ important ___________ us to protect nature. A. It; for B. It; of C. That; for 2. The elephant is ___________ to carry the heavy log. A. strong enough B. enough strong C. too strong 3. It was ___________ of him to report the illegal hunting. A. right B. for C. of 4. The baby sheep is ___________ to feed itself. A. not big enough B. enough big C. too big 5. ___________ cruel ___________ people to hunt endangered animals. A. It; for B. It; of C. That; of （四）用形式主语it改写句子 请将下列句子用形式主语it改写，保持句意不变。 1. To protect animals in danger is important. → _____________________________________________________________________ 2. To join the environmental group is helpful for us. → _____________________________________________________________________ 3. To sell products made from endangered animals is wrong. → _____________________________________________________________________ 4. To take care of injured animals is kind of you. → _____________________________________________________________________ 5. To learn about local endangered animals is necessary. → _____________________________________________________________________ （五）翻译句子 将下列句子翻译成英文（需包含本单元语法）。 1. 对我们来说，了解濒危动物很重要。 _________________________________________________________________ 2. 他帮忙筹款真是太善良了。 _________________________________________________________________ 3. 这头小象还不够大，不能自己觅食。 _________________________________________________________________ 4. 我们足够勇敢，可以阻止非法捕猎。 _________________________________________________________________ 5. 人们破坏动物栖息地是自私的。 _________________________________________________________________ 四、答案及解析 （一）用“for”或“of”填空 1. for（形容词necessary修饰动作“保护动物家园”） 2. of（形容词cruel描述猎人的品质） 3. for（形容词important修饰动作“了解濒危动物”） 4. of（形容词kind描述叔叔的品质） 5. of（形容词wrong描述他们的行为品质） 6. for（形容词helpful修饰动作“加入环保组织”） 7. of（形容词brave描述她的品质） 8. for（形容词necessary修饰动作“遵守保护规则”） 9. of（形容词selfish描述人们的品质） 10. for（形容词useful修饰动作“了解救助方法”） （二）用“形容词+enough+to+动词”完成句子 1. not big enough to eat（否定形式，“不够大，不能独自吃竹子”） 2. old enough to help（“足够大，可以帮忙保护濒危动物”） 3. too weak to walk（或not strong enough to walk，“太虚弱，走不了路”） 4. patient enough to take care of（“足够有耐心，可以照顾受伤的野鸭”） 5. not strong enough to fly（“不够强壮，不能长距离飞行”） 6. smart enough to find（“足够聪明，可以找到拯救濒危动物的方法”） 7. not tall enough to reach（“不够高，够不到鸟巢”） 8. experienced enough to deal with（“足够有经验，可以处理动物紧急情况”） 9. not clean enough to drink（“不够干净，动物不能饮用”） 10. energetic enough to collect（“足够有活力，可以为野生动物慈善筹款”） （三）选择正确的选项 1. A（形式主语it，形容词important修饰动作，用for） 2. A（enough需放在形容词后，“strong enough”表示“足够强壮”） 3. A（形容词right描述他的品质，用of，此处选项A为right） 4. A（“not big enough”表示“不够大”） 5. B（形式主语it，形容词cruel描述人的品质，用of） （四）用形式主语it改写句子 1. It is important to protect animals in danger. 2. It is helpful for us to join the environmental group. 3. It is wrong to sell products made from endangered animals. 4. It is kind of you to take care of injured animals. 5. It is necessary to learn about local endangered animals. （五）翻译句子 1. It is important for us to learn about endangered animals.（形式主语it+for结构） 2. It is very kind of him to help raise money.（形式主语it+of结构） 3. The baby elephant is not big enough to find food by itself.（形容词+enough+to结构） 4. We are brave enough to stop illegal hunting.（形容词+enough+to结构） 5. It is selfish of people to destroy animal habitats.（形式主语it+of结构） ( 1 ) 学科网（北京）股份有限公司 $