(0324)It作形式主语..pptVIP

谢 谢 聆 听 It做形式主语 Lydia ? It’s necessary for us to learn English well. ? It’s a waste of time waiting for him here. ? It’s a pity that you missed the exciting basketball match. 动词不定式 动名词 从 句 形式主语 什么是形式主语？ 形式主语是指不定式（短语）、动名词（短语）或从句在某个句子中做主语时，通常把它们放在谓语动词前，it作形式主语代替不定式、动名词、从句，置于句首，而将真正的主语放在句尾。此时为保持句子结构前后平衡，避免头重脚轻，it只起先行引导作用，本身无词义。 It is difficult to learn a second language well . It is no good crying over spilt milk. It is amazing that he won the first prize at last. It is said that they would move to America. It 作形式主语代替不定式、动词-ing短语或从句 adj p.p（过去/现在分词） n (for/of sb) to do sth doing sth 主语从句 It be + 1、It + be + adj +(for sb. / of sb./名词词组) + to do sth. a:It +be +adj +for sb to do sth 该句型中的adj通常是表示事物的特点或特征的，如 difficult，hard，easy，impossible，necessary，important等时，用for；意为做某事时是... eg: It is necessary for us to learn a foreign language. b、It+ be +adj+of sb to do sth 该句型中的adj通常用来表示人的性格特征或特点的，如 nice，good，bad，kind，silly，foolish，wise，clever， careless，rude，brave，cruel，careful， grateful等时，要用 of。意为某人做某事,某人是... eg: It is foolish of you to give up such a good chance. c: It + be +名词词组+动词不定式 eg. It is not a good habit to stay up too late. 常见句型： It takes/took sb. some time/money to do sth. Eg. It took me three days to finish reading the book. 完成作业花了我一个小时。 翻译：______________________________________ It took me one hour to finish my homework. 2、It +be+名词+动名词短语 it代替动名词ing形式 常见句型：It is no good（use）doing sth. Eg.1：It is no use learning without thinking =There is no use (in) learning without thinking. 真正的主语为 Eg. 2: It is no good crying over spilt milk. 真正的主语为 learning without thinking. crying over spilt milk. 3、It + be + that从句 it代替that从句 a: It + be +adj.+that从句 （这是that从句中最常用的一种） Its important to protect our environment. 如若形容词为 important / necessary， good/wrong ...表达一种要求，命令或者责备时，多使用虚拟语气（should +V). 1、It is time +that sb. +v-ed/ should do 1、It is time +that sb. +v-ed/ should do e