选择性必修三unit1-2 Discovering structures--动词不定式infinitives 班级：_____ 姓名：_____ Learning aims: 1. To learn the function of infinitives in a sentence. 2. To use infinitives to complete the exercises. Learning key points & difficult points: 1. Key points: to learn the function of infinitives in a sentence. 2. Difficult points: to use infinitives to complete the exercises correctly. Learning procedures: 一、不定式的定义: 不定式:是一种非谓语动词。 1.非谓语动词:是指那些在句中不能单独充当谓语的动词， 2.动词不定式在句中可以作句子除谓语之外的任何句子成分。 3.动词不定式的被动形式除了一般形式外还有其完成式和进行式。 二、不定式的形式: 基本形式： to+动词原形 其否定形式是:“not/never to do”/not do. 不定式可以带宾语或状语构成不定式短语，没有人称和数的变化。 主动语态 被动语态 一般式 进行式 完成式 完成进行式 Observe：判断下列不定式在句中作何成分 1. It is impossible to finish so much homework in a day. 2. To see is to believe. 3. His wish is to be a doctor. 4. I want to do it myself. 5. We found it difficult to work with him. 6. He always has a lot of meetings to attend. 7. He is looking for a room to live in. 8. I study hard to serve the people well. 9. In order not to be late she took a bus. 三、不定式作主语 1. 不定式作主语通常位于句首，表示具体的某次动作，谓语动词用单数。 e.g. To see is to believe. 百闻不如一见。 To get up early is necessary. 早起是必要的。 _____ is very important for everyone in society. 学习一项技能对社会上的每个人都很重要。 _____ in a month is difficult. 要在一个月内完成这座建筑是困难的。 2. 动词不定式与疑问词who, whom, whose, what, which, when, where, how等连用构成不定式短语，也可作主语。 e.g. How to use the computer is the question. 如何使用计算机是个问题。 Where to go has not been decided. 去哪儿还没有定下来。 3. 当主语较长，谓语较短时，常用it作形式主语放在句首，而将真正的主语—不定式放到谓语的后面。 e.g. It’s not easy to work out the problem. =To work out the problem is not easy.计算出这道题不容易。 It is interesting _____. 冬季里玩雪是很有趣的。 It is terrible _____. 目睹轮船沉入大海，真是太可怕了。 it作形式主语代替真正主语不定式常见于以下情况中： It is + adj. + for/of sb. to do sth. It is + n. + (for sb.) to do sth. It takes/took/will take sb. some time to do sth. It is +adj.+ for/of sb. to do sth. 1) It is ＋ adj. ＋for sb. to do sth. sb. 是to do sth.的逻辑主语 常用于表示事物的特征，用于此句型的形容词有：easy, hard, difficult, possible, important, impossible, necessary, good, bad, exciting, interesting, surprising等。 e.g. It’s important for us to keep the water clean. 保持水质清洁对我们来说是很重要的。 2) It is＋adj.＋of sb.＋to do sth. 形容词用来表示不定式的逻辑主语(sb.)的性质、特征或品德 常见的此类形容词有： kind, nice, wise, silly, polite, impolite, friendly, foolish, clever等。 e.g. It is friendly of the family to try to make me feel at home. 这家人对我很友好，使我感到宾至如归。 It is + n. + (for sb.) to do sth. 常见的名词有：pity, shame, pleasure, one’s duty, one’s job, fun, joy, good manners, bad manners等。 e.g ... ...
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