By now in your English learning journey, you have heard and used infinitives hundreds of times. For example, if someone says to you, “It is great to see you,” they are using the infinitive “to see.” If you say, “I love to learn English,” you are using the infinitive “to learn.”
在英语学习过程中，你已经听过和使用过不定式有很多次了。例如，如果有人对你说It is great to see you，他们用的就是不定式to see。如果你说I love to learn English，你就是在用不定式to learn。
Infinitives usually begin with the word “to” and are followed by a verb in its base form. An easy way to find an infinitive in a sentence is to look for the structure to + base verb. But, be careful! Not every phrase that begins with “to” is an infinitive. In fact, we use the word “to” in prepositional phrases, as in the sentence, “We went to the store.”
动词不定式通常以to开头，后面跟动词原形。在一个句子中找出不定式的一个简单方法就是找出to +原形动词的结构。但是，要注意，并不是所有以to开头的短语都是不定式。事实上，我们在介词短语中也会使用to这个词，比如在句子we went to the store中。
Although we sometimes call them “infinitive verbs,” these word forms do not act as verbs at all. Instead, they can act like nouns, adjectives or adverbs. On today’s program, we will talk about how infinitives act as different parts of speech.
虽然我们有时称其为“不定式动词”，但这些词形式上根本不充当动词。相反，它们可以作名词、形容词或副词。在今天的节目中，我们将讨论不定式在句子中充当的不同成分。
As adjectives
作形容词
Let’s begin by talking about adjectives.
我们先讨论不定式作形容词。
Just like a single-word adjective, when an infinitive acts as an adjective, it gives more information about a noun. In the following example, there are two nouns. Listen for the infinitive and think about which noun it is describing:
就像一个形容词一样，当不定式作形容词时，它主要用于修饰名词。在下面的例子中，有两个名词。看看不定式修饰的是哪个名词：
I sometimes buy magazines to read.
我有时会买杂志看。
Which noun do you think the infinitive “to read” describes?
你认为不定式to read修饰的是哪个名词呢？
The answer is “magazine.”
答案是：magazine。
When infinitives act as adjectives, we call them adjectival infinitives.
当不定式用作形容词时，我们称之为形容词不定式。
Adjectival infinitives can also be longer phrases than just to + base verb. Listen to this example:
形容词不定式也可以是更长一些的短语。请听这个例句：
The only way to get that screw out is with a power tool.
唯一能把螺丝拧出来的方法就是用电动工具。
In this case, the adjectival infinitive is “to get that screw out” and it describes the noun “way.”
此时，形容词不定式是to get that screw out，所修饰的名词是way。
As adverbs
作副词
Now, let’s find out how an infinitive can act as an adverb.
下面，我们来看看不定式是如何作副词的。
Infinitives are sometimes used to express a purpose. When they are, they carry the meaning of “for the purpose of” or “for the reason of.” In other words, they tell us why someone does something.
不定式有时用来表达目的。此时，它们就带有“为了……的目的”或“为了……的原因”的含义。换句话说，它们告诉我们为什么某人做某件事。
Just like single-word adverbs, adverbial infinitives always describe verbs. Listen to this next example and try to identify the purpose the speaker gives for his action:
就像一个副词一样，副词不定式总是用于描述动词。听下面这个例句，试着找出说话人行动的目的：
I watch Learning English videos to improve my listening skills.
我通过观看英语学习视频来提高我的听力技能。
Here, the infinitive is “to improve” but it is part of a longer phrase that acts as the adverb. So the full adverbial infinitive is: “to improve my listening skills.” It tells us the reason the speaker watches Learning English videos.
这里，不定式是to improve，但它是一个较长的短语的一部分，充当副词。完整的副词不定式是：to improve my listening skills，它告诉我们说话者看英语学习视频的原因。
Adverbial infinitives can also appear in other parts of a sentence, such as at the beginning. For instance, a speaker could say this:
副词不定式也可以出现在句子的其他位置，比如在句首。例如，说话者可以这样说：
To improve my listening skills, I watch Learning English videos.
为了提高我的听力技能，我观看英语学习视频。
As nouns
作名词
And finally, we move to infinitives as nouns. We call them nominal infinitives.
最后，我们来谈论不定式作名词。我们称其为名词性不定式。
When infinitives act as nouns, they can have several functions in a sentence. We will focus on them as direct objects and subjects. Nominal infinitives are generally part of longer phrases that, together, make a noun phrase.
不定式作名词时，在一个句子中可以起多种作用。我们把它们作为直接宾语和直接主语来看待。名词性不定式通常是较长的短语的其中一部分，它们合在一起构成名词短语。
Listen to this example and then I will tell you more:
听这个例句，然后我们再做讨论：
I want to be a millionaire!
我要成为百万富翁！
In this case, the nominal infinitive is part of a noun phrase that acts as the direct object. That phrase is “to be a millionaire.”
这时，名词性不定式是一个名词短语的一部分，充当直接宾语。这个短语就是to be a millionaire。
Nominal infinitives can also act as subjects. But this sentence structure is neither common in everyday speaking nor in formal speech or writing. Generally, you will find it in creative writing and literature.
名词性不定式也可以作主语。但这种句子结构在日常口语中不太常见，在正式的演讲或写作中也不常见。一般来说，你会在创造性的写作中和文学作品中看到。
Listen to an example:
请听一个例句：
To write music was his passion.
创作音乐曾是他的爱好。
Here, the noun phrase “to write music” (which includes the infinitive “to write”) is the subject of the sentence.
这里，名词短语to write music(其中包括不定式to write)是句子的主语。
Bare infinitives
基本的不定式、不带to的不定式
Alright, we have covered a lot. Now we just have one more thing to quickly touch on: bare infinitives.
好了，我们已经讲了很多了。现在，我们只需快速地再讲一个：基本的不定式。
Bare infinitives do not have the word “to” in front of them. Often, you will see them used with modal verbs. For instance, in the sentence, “You must follow social distancing rules,” the bare infinitive “follow” comes after the modal verb “must.”
基本的不定式前面没有to这个词。通常，你会看到基本的不定式和情态动词一起使用。例如，在You must follow social distance rules这个句子中，基本的不定式follow跟在情态动词must之后。
Well, that’s our program for today. Listen or watch for infinitive verbs wherever English is used. And, for fun, you can ask yourself if the word is being used as a noun, adverb or adjective, or if it is a bare infinitive.
好了，这就是今天的节目。在任何使用英语的场合，请留意听不定式动词。另外，为了好玩，你可以问自己这个词是作名词、副词还是作形容词，或者看看是不是一个基本的不定式。
动词不定式（动词不定式真的用作动词吗）
