高中英语语法：不定式的用法

高中英语语法：不定式的用法_ 动词不定式具有名词、形容词和副词的特征。因此在句中可以做主语、表语、宾语、宾语补足语、定语和状语。 一、不定式做主语： 1、不定式做主语一般表示具体的某次动作。===动名词doing 表示习惯的，常常的动作。 e.g: To finish the building in a month is difficult. To do such things is foolish. To see is to believe. (对等) 注: 1). 不定式作主语时,谓语用单数 2). 当主语较长，谓语较短时，常用 it 做形式主语，而将不定式放到谓语的后面。 it 做形式主语，不定式放在谓语动词之后常用于下列结构中： (1)It is/was +adj.+of sb. to do (2) It is +adj.+for sb.+to do It is easy / difficult / hard / foolish / unwise / right / wrong / unnecessary (3) it is +a +名词+ to do... It is a pity / a pleasure / a pleasant thing / ones duty / an honor / a shame / a crime / no easy job to do It takes (sb.) some time / courage / patience to do It requires courage / patience / hard work to do *注意: probable 和 possible 均可作表语，但 possible 可以用不定式作真实主语， 而 probable 不能用不定式作真实主语。 It is probable for him to come to the meeting.(错) It is possible for him to come to the meeting. It is possible / probable that he will come to the meeting. 二、不定式做表语 主语是以 aim duty hope idea intention plan job suggestion wish purpose task 等为中心词的名词词组 或以 what 引导的名词性从句表示，后面的不定式说明其内容, 不定式作表语常表示将来或现在的动作或状态。 eg :My idea is to climb the mountain from the north. Your mistake was not to write that letter. What I would suggest is to start work at once. 三 、动词不定式作宾语 以不定式结构为宾语的动词有： ask, agree, care, choose, demand, decide, expect, fail, help, hope, learn, manage, offer, plan, prepare, pretend, promise, refuse, want, wish 等只能用动词不定式作宾语 口诀(接不定式作宾语的动词) 想要学习 早打算( want learn plan) 快准备 有希望( prepare hope wish expect) 同意否 供选择(agree offer choose) 决定了 已答应(decide be determined promise) 尽力去 着手做(manage undertake) 别拒绝 别假装(refuse pretend) 失败不是属于你(fail) e.g.Tom refused to lend me his pen. We hope to get there before dark. The girl decided to do it herself. *注意:某些及物动词可用-ing 也可用动词不定式作宾语但意义不同的有 stop go on remember forget regret try mean cant help be used to