不定式作定语时,通常用来修饰名词或代词,表示动作的目的、意图或未来的可能性。以下是其主要用法:
1. 表示目的
不定式可以修饰名词,说明该名词的用途或目的。
- 例句:
- I need a pen to write with.
(我需要一支笔来写字。) - She bought a book to read on the train.
(她买了一本书在火车上读。)
- I need a pen to write with.
2. 表示未来的动作
不定式可以修饰名词,表示该名词将要发生的动作。
- 例句:
- He is the man to lead the project.
(他是将领导这个项目的人。) - This is the best time to visit the city.
(这是参观这座城市的最佳时间。)
- He is the man to lead the project.
3. 修饰抽象名词
不定式常修饰抽象名词,如 ability, chance, opportunity, way, reason, effort 等。
- 例句:
- She has the ability to solve complex problems.
(她有解决复杂问题的能力。) - This is a good opportunity to learn new skills.
(这是学习新技能的好机会。)
- She has the ability to solve complex problems.
4. 修饰代词
不定式可以修饰代词,如 something, anything, nothing, someone 等。
- 例句:
- Do you have anything to eat?
(你有什么吃的吗?) - There is nothing to worry about.
(没什么可担心的。)
- Do you have anything to eat?
5. 与被修饰词有动宾关系
当不定式与被修饰的名词有动宾关系时,若不定式动词为不及物动词,需加适当的介词。
- 例句:
- I need a chair to sit on.
(我需要一把椅子坐。) - She is looking for a place to stay at.
(她在找一个地方住。)
- I need a chair to sit on.
6. 不定式的时态和语态
不定式可以有一般式、进行式、完成式和被动式,具体形式根据语境选择。
- 一般式:to do
- He is the person to ask.
(他是该问的人。)
- He is the person to ask.
- 进行式:to be doing
- She seems to be waiting for someone.
(她似乎在等某人。)
- She seems to be waiting for someone.
- 完成式:to have done
- He is said to have finished the work.
(据说他已经完成了工作。)
- He is said to have finished the work.
- 被动式:to be done
- The task to be completed is very difficult.
(要完成的任务非常困难。)
- The task to be completed is very difficult.
总结
不定式作定语时,通常紧跟在被修饰的名词或代词后,表示目的、意图或未来的动作。需注意与被修饰词的关系,必要时添加介词。