如何使用形式主語(2)
如何使用形式主語
⒊It + v. + to do sth.
動詞不定式作主語時除動詞be以外，動詞take,cost， need,require,make,sound,occur 等也可用it作形式主語，而把動詞不定式放在后面。例如：
It took us three years to complete the project. 我們花費三年時間才完成了這項工程。
It sounds reasonable to do it this way.聽起來這樣做有道理。
It needed hard work to finish the job. 要完成這項工作需要努力地工作。
It didn,t occur to me to ask him to help me. 我根本沒想到要找他幫忙。
動名詞作真正主語
用于這種形式的是一些特定的形容詞和名詞。例如：
It was nice meeting you. 見到你真高興! (分別時用)
它與不定式作真正主語的區別在于，動名詞說到的動作已經發生。例如：
It is nice to meet you. (剛剛見面時用)
it 作形式主語，動名詞作真正主語主要用于下列句型：
It's +n.(名詞或名詞短語)/adj.(形容詞)+ doing sth.
1)下列形容詞后常用動名詞作真正主語：nice,good,useless,hard,foolish,enjoyable,worthwhile等。例如：
It is nice talking to you. 跟你交談真是愉快。
It's foolish behaving like that. 這樣的表現是很愚蠢的。
It is useless doing that. 那樣做沒用。
2)下列名詞或名詞短語作表語時常用動名詞作真正主語：use,good,fun,a waste of,job,task等。例如：
It's a waste of time doing this. 這樣做是浪費時間的。
It's no good (use) doing that. 那樣做沒好處(沒用)。
It's an awful job doing this. 做這事真是一件可怕的差事。
It's fun doing this. 做這事真有趣。
It is not an easy task doing this work. 做這工作真非易事。
名詞從句作真正主語
用it 作形式主語的結構主要用于下列句型：
It +謂語+名詞從句(主語從句、表語從句、同位語從句)
⒈It is +名詞+從句： 這樣的名詞有a fact,a surprise,an honor(非常榮幸)，a pity,common knowledge(常識)等。例如：
It is common knowledge that the full moon brings fair weather. 皓月兆天晴，這是常識。
It is a surprise that you gave such an answer to the question. 你對這個問題作了這樣的回答，令人吃驚。
⒉It is +形容詞+從句: 這樣的形容詞有natural,true,strange,necessary,important,obvious(很明顯)，certain,wonderful,funny,possible,likely,probable等。例如：
It is certain that free medical care will be given to most people in our city. 我們城市的多數人將享受免費醫療，這是一定的。
It is probable that he has known everything. 很可能他什么都已經知道了。
⒊It +動詞+從句： 這樣的動詞有seem,happen,appear,look,matter,make,strike,occur(突然想起)等。
It appeared that he had a taste for music. 看來他對音樂有一定的鑒賞力。
It made us very happy that she was saved.她能化險為夷令我們大家很高興。
⒋It + be + 分詞+從句： 這樣的分詞有 said(據說)， reported(據報道)，believed(人們相信)，known(眾所周知)，decided(已決定)，proved(已證實)，thought,expected,annouced,arranged,amusing,puzzling,striking等。例如：
It is said that Li Hao has been to Europe.據說李郝去過歐洲。
It was amusing that a rabbit ran out of the empty box on the desk.桌上的空盒子里竟然跑出來一只兔子，太有趣了。
需要說明的是，大部分連接詞引導的主語從句都可以用 it充當形式主語。例如：
It remains unknown when they are going to get married. 他們何時結婚依然不明。
It says in the newspaper that the enemy has been defeated. 報紙上報導敵人被打敗了。
形式主語：
It +be+(the)+adj.+for sb.+to do sth.
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