Itis形容词for of sb to do sth两种结构-2025-2026学年八年级英语下册语法重难点精讲（沪教版）

8下沪教上海版 【语法专版】 重难点精讲 语法专版 【语法专题】Itis+形容词+for/ofsb.todo sth.两种结构 初中沪教上海版八年级下册 语法精讲 语法概述：Itis+形容词+for sb.to do sth.表示做某事对某人来说是怎样的，形容词描述事物特 征；Itis+形容词+ofsb.to do sth.表示某人做某事是怎样的，形容词描述人的品质，两种结构中 it均为形式主语，真正主语是后面的动词不定式短语to do sth.。 一、重难点讲解 重难点一：for和of的选择依据讲解： 当形容词描述事物特征或行为性质（如difficult,important,.necessary等)，不直接修饰人时，用for sb.结构，sb.仅为动作的执行者。 It is necessary for students to finish homework on time..(“必要的”描述完成作y业这件事的性质) 当形容词描述人的品质或性格（如kind,clever,brave,foolish等），可直接修饰人时，用ofsb.结构， sb.同时是形容词的逻辑主语。 It is kind of you to help the old lady cross the road.(“善良的”描述人的品质) 真题再现： 1.(2024上海杨浦期末，沪教上海版)It is important us to learn English well. A.for B.of C.with D.to 答案：A解析：important描述学英语这件事的重要性，用for。 2.(2023 上海闵行月考，沪教上海版)It was clever Tom to solve the math problem quickly. A.for B.of C.to D.with 答案：B解析：clever描述Tom的聪明品质，用of。 8下沪教上海版 【语法专版】 重难点精讲 重难点二：t的指代作用及句子结构讲解： it在此结构中作形式主语，真正的主语是后面的动词不定式短语to do sth.,避免句子头重脚轻。 基本结构：It+be+形容词+(for/ofsb)+to do sth, It is dangerous for children to play near the river.(it to play near the river) 注意：of结构可转换为“sb.+be+形容词+to do sth.”,for结构不可。 You are kind to help the old lady.(=It is kind of you to help...) It is difficult for him to swim.(不可转换为He is difficult to swim.) 真题再现： 1.(2024 上海浦东期中，沪教上海版)is difficult us to finish the work in two days, A.It;for B.That;for C.It;of D.This;of 答案：A解析：it作形式主语，difficult描述事物性质，用for。 2.(2023上海徐汇期末，沪教上海版)It is polite youyour seat to the elderly. A.of;to give B.for;give C.of,give D.for;to give 答案：A解析：polite描述人的礼貌品质，用of:第二个空需用不定式作真正主语。 重难点三：形容词后介词搭配及句式转换讲解： 部分形容词后固定搭配介词，需注意与for/of的区别。如ready for,,sorry for,,good for等，但此类 结构非本语法点范畴。 本结构中形容词直接接for/of,后接不定式。 易错点：避免混淆“be+形容词+for sb.todo”与“be+形容词+for+名词”。 It is good for health to exercise..(本结构，for后接sb.) Milk is good for health.(普通搭配，for后接名词) 否定句结构：在be动词后加not。 It is not easy for him to drive a car. 疑问句结构：将be动词提前。 Is it important for us to keep trying? 真题再现： 1.(2024上海长宁月考，沪教上海版)It is not right_you litter in public places.. A.for;to drop B.of;to drop C.for;drop D.of,drop 8下沪教上海版 【语法专版】 重难点精讲 答案：B解析：right描述人的行为是否正确，用of:不定式作真正主语用toop。 2.(2023 上海静安期末，沪教上海版)一Is it necessary_me_there on time? -Yes,the meeting will start at 8:00 sharp. A.for;to be B.of be C.for;be D.of,to be 答案：A解析：necessary描述事物性质用for;不定式作主语需用tobe。 易错点综合演练 I.单项选择（直击重难点） 1.It is necessarystudents to follow school rules. A.for B.of C.with D.to 2.It was brave Lucy to save the little girl from the fire. A.for B.of C.to D.with 3.is important us to protect the environment A.It;for B.That;for C.It;of D.This;of 4.It is polite you"thank you"when someone helps you. A.of;to say B.for;say C.of,say D.for;to say Ⅱ用所给词的适当形式填空（强化句型结构） 1.It is kind of you(help)me with my English 2.Is it difficult for him (climb)the mountain? 8下沪教上海版 【语法专版】 重难点精讲 3.It is not right of them (laugh)at others. 4.(be)it necessary for us(attend)the meeting tomorrow? Ⅲ.短文填空（综合运用语法点） 用for,of或所给词的适当形式填空，使短文完整通顺。 It is important 1.us to learn how to be polite.For example,it is polite 2.you 3.(greet)your teachers when you meet them.It is kind 4.people 5.(help)those in need.It is necessary 6. students 7.(finish)their homework on time.Remember,being polite makes the world a better place. V.连词成句（聚焦句型结构） 1.is,for,it,important,to,learn,English,well,us,(. 2.clever,of,solve,the,problem,it,is,him,to,( 3.it,is,for,difficult,finish,the,work,in,an,hour,me,to,(. 4.kind,you,help,are,to,others,(. V.按要求改写句子（巩固否定、疑问句式） l.It is easy for her to sing this song.(改为否定句) 2.It is good of you to share your things with others.(改为一般疑问句并作肯定回答) 3.It is necessary for us to keep quiet in the library.(改为同义句，用sb.+be+形容词+to do sth. 结构，若不可转换则写原句) 4.It is dangerous for children to play with fire.(对划线部分提问) 参考答案 I.单项选择：1.A2.B3.A4.A Ⅱ.用所给词的适当形式填空：1.to help2.to climb3.to laugh4.Is,to attend 8下沪教上海版 【语法专版】 重难点精讲 Ⅲ.短文填空： 1.for 2.of 3.to greet 4.of 5.to help 6.for 7.to finish IV.连词成句： 1.It is important for us to learn English well 2.It is clever of him to solve the problem. 3.It is difficult for me to finish the work in an hour. 4.You are kind to help others. V按要求改写句子： 1.It is not easy for her to sing this song. 2.Is it good of you to share your things with others?Yes,it is. 3.It is necessary for us to keep quiet in the library.(不可转换为We are necessary to keep quiet in the library.） 4.What is dangerous for children to do? 5