Definition of the Infinitive Verb Form
When we use the word 'to' before a verb in a sentence, we are using the infinitive verb form. However, what can be confusing is that the infinitive phrase -- 'to' plus a verb -- does not act like a verb at all but rather takes on the role of a noun, adjective or adverb in a sentence. For example, we have this famous sentence from Hamlet: 'To be or not to be: that is the question.'
The phrase 'to be' is acting as the subject of the sentence. It is as if the verb phrase puts on the costume of a noun, adjective or adverb and plays the role of a part of speech other than itself.
Any verb that is preceded by the word 'to' is an infinitive. Here are some examples: 'to love, to eat, to run, to believe, to follow, to laugh, to stare, to wonder.'
Infinitives as Nouns
Here are some examples of infinitives that are used as nouns in sentences:
'To run a marathon was Amelia's greatest dream.' Here, the phrase 'to run' is used as the subject of the sentence.
'Monica wanted to score five goals in the soccer game.' In this sentence, 'to score' acts as a direct object. Remember that direct objects are nouns; they can answer the question 'who' or 'what' and receive the action of the subject.
Infinitives as Adjectives
Now, we will take a look at how infinitives can be used as adjectives in sentences. Take a look at these examples:
'Terrence lacked the motivation to succeed.' In this sentence, the phrase 'to succeed' modifies the noun 'motivation' and takes the role of an adjective.
'Paco disagreed with Molly's penchant to interrupt people when they were speaking.' The phrase 'to interrupt' gives us more information about or modifies the noun 'penchant.'
Infinitives as Adverbs
Adverbs can modify verbs, adjectives or other adverbs in sentences. Here are some ways infinitives can be used as adverbs:
'Jimmy must wait to hear the results of the race.' In this sentence, the infinitive phrase 'to hear' modifies the verb 'wait.' Therefore, it's a good example of how an infinitive can be used as an adverb.
Take a look at another sentence: 'It's good to know how to put out a fire.' The word 'good' is an adjective, and 'to know' modifies it; thus, it's an adverb.
Problems to Avoid with Infinitives
The first potential problem to avoid is mixing up infinitive phrases with prepositional phrases. Remember that an infinitive phrase is the word 'to' followed by a verb. A prepositional phrase may start with the word 'to,' but it is followed, eventually, by a noun, as in the phrase 'to the store.' These two types of phrases take on completely different roles in sentences.
The second problem to avoid is the split infinitive. As it sounds, a split infinitive occurs when the word 'to' is separated from the verb in the infinitive phrase. Here is an example:
'Cynthia chose to boldly try a new food.' It sounds really awkward, doesn't it? The infinitive 'to try' is separated by the word 'boldly.' Here is a better way to write the sentence: 'Cynthia boldly chose to try a new food.'
When we use the word 'to' before a verb in a sentence, we are using the infinitive verb form. Remember that what makes infinitives so tricky is that they look like verbs, but act like other parts of speech such as nouns, adjectives or adverbs. Identifying infinitive verb forms is fairly easy as they are preceded by the word 'to.' But make sure you don't get them mixed up with prepositional phrases that can also begin with 'to.' Now, can you recognize infinitives when you see them? That was the question Hamlet should've been asking!
After you are done with this lesson, you should be able to:
- Identify the infinitive form of a verb
- Recite examples of infinitives used as adjectives, nouns, and adverbs
- List some of the common errors when using infinitives
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Infinitive Verb Form: Activities
The below activities are designed to help students continue to learn about infinitive verbs and their grammatical functions.
Identifying Infinitive Verbs
In the paragraph below underline every infinitive verb used. Then, determine what part of speech the infinitive verb is functioning as (i.e. a noun, an adjectives, or an adverb). Once you have determined the latter, write the part of speech above the infinitive.
- To explain complex math problem was Ms. Henderson's greatest delight. In fact, Ms. Henderson solved complex math problems outside of class to help NASA scientists. I like to wait after class to talk with Ms. Henderson—her stories about working with NASA are fascinating! Also, spending time with Ms. Henderson is a great way to practice my math.
- To explain: noun (subject)
- to help: adverb (describes the verb solved: why did Ms. Henderson solve math problems outside of class?")
- to wait: noun (direct object)
- to talk: adverb (describes the verb like: why do I like to wait after class?)
- to practice: adjective (describes the noun ''way'')
Writing Infinitive Verbs
Write a short story of at least 250 words about a time you were surprised. In your writing, include at least three infinitive verbs. At least one infinitive verb should function as a noun; at least one should function as an adjective, and at least one should function as an adverb. Underline each infinitive verb you include and indicate its part of speech above the infinitive.
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