不定式由“ to+ 动词原形”构成 , 其否定形式是“ not/never to 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 ,但有时态和语态的变化。不定式可以作主语、宾语、状语、表语和定语，但不能单独作谓语。不定式的逻辑主语有时用“ for+ 名词或代词宾格”构成。不定式一般式完成式进行式主动语态 被动语态 to do to be done to have done to have been done to be doing to be being doing壹.解释(1) 不定式的一般形式所表示的动作，通常与谓语的动 作（状态）同时（或几乎同时）发生，或是在它之 后发生。(2) 如果谓语表示的动作（情况）发生时，不定式表示的动作正在进行，这时不定式就要用进行式。(3) 如果不定式的动作发生在谓语动词之前，就要用完成式。They pretended to be studying when the teacher came in.I`m sorry to have kept you waiting.I want to have a holiday as soon as possible .动词不定式的作用 Functions of Infinitive 主语 (subject) 宾语 (object) 表语 (predicative) 定语 (attribute) 状语 (adverbial)动词不定式归纳一、不定式做主语时，谓语动词常常用单数1 、“ To do …” 放在句首做主语 eg: To drink enough water every day is very important.2 、如果动词不定式太长，常用 it 作形式主语“ to do …” 放在句末做真正主语，用“ It” 放在句首引导 eg.1 ： It is very important to drink enough water. eg.2: It take you 5 minutes to get there. 不定式做真正主语的两个特殊句型* It is/was +adj.+of sb. to do… eg: It is brave of him to save the girl in the water.注意：在此句型中， adj. 只能用可以修饰行为、动作及人物的形容词。例如： kind, nice, good, brave, clever, wise, stupid, foolish, honest, careless, cruel, generous etc.*It is +adj.+for sb.( 用宾格 ) +to do… eg.1: It is not difficult for us to learn English well. eg.2: It is right for him to work here.注意：这里的 adj. 不能表示人的性质，只能表示某事或某物的性质。例如： difficult, wonderful, meaningful, painful,useful二、不定式作宾语 1 、不定式经常放在及物动词...
