http://www.engvid.com/ A grammar lesson for advanced students of English. There are many ways to use infinitives in English. Did you know that an infinitive can be used as a subject, object, subject complement, adjective, or adverb? It's true. In this grammar lesson, I look at these five common ways to use infinitives. Once you're done with this lesson, don't forget to check out my lessons on common verbs followed by infinitives, and active and passive infinitives.
http://www.engvid.com/english-grammar-5-ways-to-use-infinitives/

TRANSCRIPT

Hey, everyone. I'm Alex. Thanks for clicking, and welcome to this lesson on five ways to use infinitives. To refresh our memory, an infinitive in English is "to" plus the base verb. So for example, "to run", "to play", " "to hide", "to eat", "to go" -- these are all examples of infinitives. Now, despite the fact that infinitives refer to actions, they often perform the same function as nouns. So let's look at the five ways that we can use infinitives in English.

So here, we have -- infinitives can be subjects. They can be the subject of a sentence. This is a very formal structure, but it is possible. For example, "To do the right thing is not easy." "To learn a new language is helpful." So here, we have "to do", "to learn", okay? And again, these are infinitives. And this is a very formal structure. So in speaking, we don't often use infinitives as subjects, but I want you to know that it is possible. However, in speech, when we use infinitives in this kind of context, we usually put them in the middle of an "it" phrase. So for example, instead of saying, "To do the right thing is not easy", we say, "It's not easy to do the right thing." Or instead of, "To learn a new language is helpful", in common speech, we say, "It's helpful to learn a new language." Okay? So again, this is formal; this is much more common. Okay?

Second of all, infinitives can be objects. So for example, "I want to help you." Here, we have "I", "the subject, "want", the verb, "to help" -- and "to help", here, would be an object. Okay? So, "I want to help." "They love to travel." And in both of these sentences, the infinitive is actually the object of the sentence.

Here, No. 3, infinitives can be subject complements. Now, a "complement" is basically something that gives you more information about the thing you're talking about. In this situation, we want more information about the subjects of these sentences. So for example, "Her job -- okay." "Tell me more about her job." "Her job is to assist you." So if this is a receptionist, for example, her job is to assist you. You're giving more information about her job. "My dream -- my dream is -- what is your dream? Give me more information about your dream." "My dream is to open a business." Okay? So here, we have infinitives used as subject complements.

Now, these last two -- infinitives can be adjectives and adverbs -- you might be surprised because when you think of adjectives, you probably think of colors or words like "happy" or "sad" or "cold" or "hot". However, if you're not comfortable with thinking of them as adjectives, maybe think of them as object complements. And that's another way to look at it if mentally it doesn't make sense for an infinitive to be an adjective. However, let's look at an example. "I told you" -- so here, we have subject, verb, object. "I told you to wait." So what did I tell you? I told you to wait. So you're describing what you told this person. "He wants me to leave." What does he want me to do? He wants me to leave. So I'm describing what he wants. Again, adjectives are description words, right? Describing what he wants. I'm describing what I told you. Okay?

And finally, adverbs -- so again, adverbs give more information about a verb. In thinks situation, "We must study" -- we have the verb "study". "Why must we study?" "To learn." So here, you have verb plus infinitive. And here, "I want to learn to sing." So here, "I want to learn" -- "to learn" is an object. And we want to give more information about the object and why we do it. So here, we have "to sing".

Now, again, grammatically, if you don't understand "adjective", "adverb", "subject complement", it's not -- I don't want to say it's not important, but in everyday speech, it's not that important to be able to say, "This is an adjective"; "this is an adverb"; "this is a complement." The most important thing is do you understand these sentences when you see them? Do you understand the meaning of, "We must study to learn"? "I want to learn to sing"? As long as you understand what the sentences mean, the grammatical language is not as important, as long as you know how to use it in different parts of the sentence. Okay?