Unit 2 Great minds第 3 课时 单元语法讲解栏目导航巩 固 习 题动词不定式 动词不定式（Infinitives）即小品词 to 后面跟动词原形，写作“to do（sth.）”。本单元重点讲解不定式作后置定语、不定式作主语、不定式作表语。 （1）名词后跟动词不定式（Infinitives after nouns） 名词后跟动词不定式，也就是说动词不定式充当后置定语。例如： I have some questions to ask you. 我有一些问题要问你。 （ask you some questions，此时不定式与 questions 构成动宾关系。） Tim is always the first to arrive at school. 蒂姆总是第一个到校。 （the first arrives at school，此时不定式与 arrives 构成主谓关系。） I have a dream to help the children in the poor villages. 我有一个帮助贫困农村孩子的梦想。 （此时不定式 to help the children in the poor villages 修饰 a dream） 注意：很多情况下，不定式后的介词不可省略。例如： This is a good pen to write with. 这支钢笔很好写。（write with a pen） Amy is a nice person to work with. 艾米很好共事。（work with a person） （2）动词不定式作主语（Infinitives as subjects） 动词不定式可充当主语。例如： To see is to believe. 眼见为实。 To learn a foreign language well is necessary. 学好一门外语是有必要的。 【句型】to do sth. is adj.一般都可以改写成 It is adj. to do sth.，此时 it 充当形式主语。例如： To make snowmen in winter is interesting. 冬天堆雪人是有趣的。 =It is interesting to make snowmen in winter. 此外，要注意下面两个句型的区别：It is adj. for sb. to do sth.和 It is adj. of sb. to do sth. It is important for us to look after ourselves well. 照顾好我们自己是重要的。 =To look after ourselves well is important for us. It is kind of you to help me. 帮助了我，你真好。 =You are kind to help me. 另外，句型 It takes（sb.）time to do sth. 中的 It 也作形式主语。例如： It takes me one hour to prepare lessons every day. 每天我花一个小时备课。 （3）be 后面跟动词不定...
