概述 动词不定式(to+动词原形)是一种非谓语动词形式,它不能单独作谓语,但可 以有自己的宾语、状语、补足语等,并和它们一起构成不定式短语,在句中作主语 谓语、表语、宾语、定语、状语和补足语,动词不定式也有时态和语态的变化,是 三级常考点之一。 1.不定式构成谓语 不定式构成谓语有下面几种方式: 1)不带to的不定式和某些助动词构成谓语 Shall I help you? I will be back right now 2)不带to的不定式和情态动词构成谓语 We must keep this in mind How can we convince him? 3)不定式和某些动词构成谓语 She happened to live in the same area You appear to have traveled a lot 4)不定式和某些形容词构成谓语 Madame is sure to be right He is certain to return 5)不定式和某些被动结构构成复合谓语 He is said to have been in China many times This was thought to be impossible 2.不定式作主语 不定式可以作主语,不定式作主语谓语用单数 To compromise appears advisable To stop the work now seems impossible 但在更多情况下都用it作先行主语,而把不定式这个真正的主语放到句子后面 去,这样可使主语不至显得太长,避免头重脚轻的现象,常见的这类句子有下面几 种 l)tbe+形容词+不定式 It is hard to say which is bette It's foolish to act like that 2lt+be+名词+不定式 It's an honour to meet you 3)t+动词(宾语)+不定式2 概述 动词不定式（to+动词原形）是一种非谓语动词形式，它不能单独作谓语，但可 以有自己的宾语、状语、补足语等，并和它们一起构成不定式短语，在句中作主语、 谓语、表语、宾语、定语、状语和补足语，动词不定式也有时态和语态的变化，是 三级常考点之一。 1. 不定式构成谓语 不定式构成谓语有下面几种方式： 1)不带 to 的不定式和某些助动词构成谓语 Shall I help you? I will be back right now. 2)不带 to 的不定式和情态动词构成谓语 We must keep this in mind. How can we convince him? 3)不定式和某些动词构成谓语 She happened to live in the same area. You appear to have traveled a lot. 4)不定式和某些形容词构成谓语 Madame is sure to be right. He is certain to return. 5)不定式和某些被动结构构成复合谓语 He is said to have been in China many times. This was thought to be impossible. 2. 不定式作主语 不定式可以作主语，不定式作主语谓语用单数： To compromise appears advisable. To stop the work now seems impossible. 但在更多情况下都用 it 作先行主语，而把不定式这个真正的主语放到句子后面 去，这样可使主语不至显得太长，避免头重脚轻的现象，常见的这类句子有下面几 种： 1)It+be+形容词+不定式 It is hard to say which is better. It’s foolish to act like that. 2)It+be+名词+不定式 It’s an honour to meet you. It’s our duty to obey the law. 3)It+动词（宾语）+不定式