04 Unit 1 Fighting Stress 动词不定式作主语和表语-英语沪外版选择性必修第三册

Unit 1 Fighting Stress 1 infinitives used as subject and predicative 动词不定式作主语和表语 Introduction 动词不定式的基本结构式是to do , 其中的do代表动词的原形， do可以是任何其他的动词，因为动词do是不固定的，所以我们把它称为动词不定式，它的否定形式是“not to do”。动词不定式没有人称和数的变化，但有时态和语态的变化。动词不定式不能单独作谓语，可以作主语、宾语、表语、定语、补语等。如： To be a doctor is hard. (不定式作主语) His work is to drive a car. (不定式作表语) I want to tell you a story. (不定式作宾语) She was the last student to leave the classroom.(不定式作定语) Tell him to leave here next week.(不定式作补语) 动词不定式作主语 01 节标题页? 4 1. 动词不定式作主语，表示具体的、一次性的或者表示将来含义的动作，且谓语动词常用单数。如： To be calm in danger is very important/significant. To win the game is possible. To see is to believe. To work with him is a great pleasure. 动词不定式作主语 01 5 01 2. 动词不定式短语作主语时，为了保持句子平衡，往往用it作形式主语，而将动词不定式短语置于句末。如： It is important to learn English well. It would be a waste of time to argue with him. 其常见句型如下： 动词不定式作主语 6 1. It＋is＋名词＋to do sth It’s our duty to protect the natural environment. 2. It took sb some time/money＋to do sth It took us three hours to finish the report. 3. It＋be＋形容词＋for/of sb＋to do sth It’s very generous of you to donate us a large sum of money. It is necessary for children to form good habits at an early age. 4. It seems/appears)＋形容词＋to do sth It seemed impossible to catch up with them in 20 minutes. 01 动词不定式作主语 7 练习：用 it 做形式主语改写下面句子 (1) To speak French well isn’t an easy job.  (2) To improve our teaching method is very important. (3) To work with her is a great pleasure.  (4) To look up every new word would be a waste of time. It isn’t an easy job to speak French. It is very important to improve our teaching met