It做形式主語講解

1、It做形式主語做形式主語 Its necessary for the young to master two foreign language. Its a waste of time talking to her any more. Its a pity that you missed the exciting football match. 動詞不定式動詞不定式動名詞動名詞從從 句句形式主語It 作為作為形式主語形式主語的用法的用法當當 不定式、動名詞、從句不定式、動名詞、從句 等用作等用作句子主語時，為保持句子平衡，通句子主語時，為保持句子平衡，通常把真正的主語放在句末，而在句常把真正的

2、主語放在句末，而在句首使用形式主語首使用形式主語it.拒絕是令人遺憾的拒絕是令人遺憾的.記住這一點是很重要的記住這一點是很重要的.Its a pity to refuse.Its very improtant to remember this一、代替動詞不定式做形式主語It +be +adj.+（for sb.）to do sth. 此處adj. 通常為描述事件事件的形容詞：easy，difficult，hard，necessary，impossible， important，natural, likely，obvious，useful，useless，dangerous做某事是Its nec

3、essary for us to master a foreign language. It +be+ adj.+ of sb. to do sth 此處adj. 通常為描述人人的形容詞：kind，nice，rude，cruel，careless，foolish，stupid，wise，crazy某人做某事，某人是 eg. Its foolish of you to drive a car after drinking. Its very kind of you to help me with my English.It + be +名詞詞組+動詞不定式eg. It is not a good

4、 habit to stay up too late. 常見句型：It takes/took sb. some time/money to do sth.It is no good crying over spilt milk.It is no use casting pearls before swine .覆水難收覆水難收不要明珠暗投，對牛彈琴不要明珠暗投，對牛彈琴構成如下結構：構成如下結構：It is +no use/no good/not any good/not any use+ doing sth.二、代替動名詞作形式主語It + be + 名詞詞組 + 主語從句這類名詞有：a f

5、act, a pity, a shame, an honour，a question，a surprise，common knowledgeeg.Its common knowledge that people cannt live without water . 三、代替從句做形式主語It + 不及物動詞 + that（as if）-從句這類不及物動詞有：look，seem，appear，happen，occureg.It seems that he does not tell the truth. It is time +that sb. +v-ed/ should do Eg. Its

6、time that you went to bed Its time that you should go to bed. Its necessary/ impossible/ important/ natural that sb. (should) do Eg. Its important that we (should) keep the balance of nature.It + be +adj.+that-從句It + be +-ed（過去分詞）+ that-從句It is said that 據(jù)說It is reported that 據(jù)報道It is supposed that 據(jù)推測It is hoped that 希望It is well known that 眾所周知It is generally considered that普遍認為It is suggested that 有人建議練習：把下列格局轉換為it做形式主語的句子1.He was rude to say so.2.Trying again is of use.3.When and where to hold the party hasnt been decided.It was rude of