1. 不定式(Infinitive)
一、不定式的定义与功能
不定式是动词的一种形式,通常由“to + 动词原形”构成。它并不表示动作的时态、语态或主语的关系,而是作为名词、形容词或副词在句中发挥其他语法功能。
不定式的基本功能:
- 作为名词:充当主语、宾语或表语。
- 作为形容词:修饰名词。
- 作为副词:修饰动词、形容词或其他副词,表示目的、原因、方式等。
二、不定式的构成与用法
1. 作为主语
不定式可以作为句子的主语,表示一个动作或行为的整体概念。
例子:
- To travel around the world is my dream.
(环游世界是我的梦想。) - To study hard is important.
(努力学习很重要。)
2. 作为宾语
不定式常用作动词的宾语,尤其是表示意图、计划、愿望等的动词后面。
例子:
- She wants to visit her grandparents.
(她想拜访她的祖父母。) - I decided to go to the cinema.
(我决定去看电影。)
3. 作为表语
不定式也可以用作系动词后的表语,描述主语的状态或属性。
例子:
- His goal is to become a doctor.
(他的目标是成为一名医生。) - The plan is to finish the project by next week.
(计划是在下周前完成这个项目。)
4. 作为宾语补足语
在某些动词(如使役动词和感官动词)后,不定式可以作为宾语补足语,进一步说明宾语的动作或状态。
有些动词后,宾语补足语可以用动词的原形而不是不定式,尤其是感官动词(如 "see", "hear", "feel")和使役动词(如 "make", "let", "have")。(如"help", "need", "would rather")在这些情况下,动词原形直接跟在宾语之后,不需要 "to"。
例子:
- I heard him sing a song.
(我听见他唱了一首歌。) - They made her cry.
(他们让她哭了。)
如在使役动词 “make” 后,作宾补的动词不定式要省略 “to”,即 “make sb. do sth.”,表示 “使某人做某事”.
类似用法的使役动词还有 “let”(Let him go. 让他走)
更多例子:
- 使役动词 使役动词如 "make", "let", "have" 后面常接动词原形。
- I made him stay.(我让他留下。)
- She let me go early.(她让我早点走。)
- They had me do the work.(他们让我做这项工作。)
- 感官动词
感官动词如 "see", "hear", "feel", "watch" 等后面通常接动词原形,表示感官的动作。
- I saw her dance. (我看见她跳舞。)
- He heard them sing. (他听见他们唱歌。)
- I felt him touch my hand. (我感觉到他摸了我的手。)
- We watched the children play. (我们看着孩子们玩耍。)
- 其他动词 一些动词,如 "help", "need", "would rather", 也可以后接动词原形。
- She helped me carry the bags. (她帮我提包。)
- I would rather stay at home. (我宁愿待在家里。)
- I need you explain this. (我需要你解释一下这个。)
5. 作为定语
不定式可以修饰名词,表示目的或描述其性质。
例子:
- I have a lot of work to do.
(我有很多工作要做。) - This is the book to read.
(这是要读的书。)
6. 作为状语
不定式也可用作状语,表示目的、原因、结果等。
例子:
- He went to the store to buy some groceries.
(他去商店买一些杂货。) - She studies hard to pass the exam.
(她努力学习以便通过考试。)
三、常见不定式短语
不定式可以与其他词语一起构成不定式短语,表示更具体的意义。
例子:
-
be able to
(能够)
She is to be able to speak three languages.
(她能说三种语言。) -
have to
(必须)
I have to finish my homework before dinner.
(我必须在晚餐前完成作业。) -
want to
(想要)
I want to go for a walk.
(我想去散步。) -
decide to
(决定)
They decided to go on vacation next month.
(他们决定下个月去度假。)
通过理解不定式的用法和构成,可以灵活运用不定式来表达不同的语法功能。