动词不定式的五种用法

有的同学会有疑问说在写作中我们到底什么时候可以用‘To+do’的形式。那么我们今天就来看看不定式（infinitives）都可以在句子中充当什么角色。

什么是不定式（infinitives）？
在英语语法中，动词不定式是指动词的一种不带词性变化的形式。也就是说动词原形在带上‘to’这个小伙伴后就不再受主语和时态的影响，始终保持‘to+base verb’的形式。也可以理解为To后面永远都是动词原形。
Eg：He always helps mother to do housework.
Mom asked him to finish homework in this morning.
二、不定式可以在句子中扮演什么成分（动词不定式的五种用法）？
The infinitive often performs the same function as the nouns.
动词不定式可以在句子中做主语（Subjective）
Eg: To do something is not easy.
To learn English is not easy.
It is not easy to learn English.
It is helpful to learn another language.
这里的it是做形式主语，在句子中并无实际语义。
练习：
1. It’s our duty _________ the room every day.
A. to clean B. cleaned C. clean D. cleans
2. It’s hard for us _________ English well.
A. learn B. learns C. to learn D. learning
B．动词不定式在句子中做宾语（Objective）
Eg: I want to help you.
They love to travel.
练习：
1. He wants ______ some vegetables.
A. buy B. buying C. to buy D. buys
2. Don’t forget ______ your homework with you when you come to school.
A. to bring B. bringing C. to take D. taking
C．动词不定式作主语补足语（subject complements）:意在给你更多关于你所讨论的事的信息
Eg：His job is to assist you.
My dream is to open a business.
练习:
1. Robert often asks us ______ his Chinese, so his Chinese is much better than before.
A. help him B. to help him with C. to help with D. helps him with
2. Mr Li often teaches his Japanese friends ______ Chinese food.
A. cook B. cooks C. to cook D. cooked
D. 动词不定式做形容词（adjective）
Eg：I told you to wait. 这里的不定式是在形容‘what I told you’。
He wants me to leave. 这里是在形容‘what’s he want’。
练习：
1. He wants ______ some vegetables.
A. buy B. buying C. to buy D. buys
2. Don’t forget ______ your homework with you when you come to school.
A. to bring B. bringing C. to take D. taking
3. He found it very difficult ______.
A. sleeping B. sleepsC. slept D. to fall asleep
E、动词不定式做副词（Adverbs）: 给了更多关于动作的信息
Eg: We must study to learn. (解释了why we study)
I want to learn to sing. (解释了what you want to learn)
练习：
1. Robert often asks us ______ his Chinese, so his Chinese is much better than before.
A. help him B. to help him with C. to help with D. helps him with
2. Mr Li often teaches his Japanese friends ______ Chinese food.
A. cook B. cooks C. to cook D. cooked
以上就是关于动词不定式的五种用法，希望能对大家的写作有所帮助。