In English, there are two main ways that we use adjectives (words that describe ) together with infinitive verbs (to + verb):
The infinitive verb is the complement of an adjective (the infinitive completes or enriches the meaning of the adjective):
This toddler is able to walk.
The adjective describes the infinitive action ( the adjective adds information about the infinitive):
It is safe to cross the street here.
In this post, we’ll discuss how to form each kind of sentence and introduce you to some of the adjectives in each group. Are you ready to get started? Let’s have a look!
To use an adjective with an infinitive complement, follow the sentence pattern below:
subject
be
adjective
infinitive
I am sorry to hear that.
Unlike other adjectives in English, an adjective with an infinitive complement never comes before the noun it describes. An adjective that works with an infinitive can only come after a verb:
✅ I have a nice dog.
❌ I have a happy to eat dog.
✅ My dog is nice.
✅ My dog is happy to eat.
The verb is almost usually be, but it can sometimes be another linking verb like seem, appear, or look.
When an adjective has an infinitive complement, the adjective describes the . The infinitive makes the meaning of the adjective more specific. For example:
I am so sorry to hear that!
Joe was kind enough to bring cookies!
Andre is able to climb the rope.
Bill was prepared to come to the vacation house.
In sentences like this, the subject of the sentence usually subject of the infinitive verb:
The chickens are excited to eat their dinner.
Patrick was happy to be home.
The assignment was ready to be turned in.
A few adjectives of opinion, like ready, delicious, or ugly can describe the object of an infinitive. For example:
The assignment was ready to turn in.
This cake is delicious to eat.
The trash is ugly to see.
Also, when an adjective describes an action, the object of the infinitive will often be the subject of the sentence. Keep reading to learn more!
Here are some common types of adjectives that are used with infinitive complements:
Adjectives for emotions felt by the nouns they describe:
e.g. happy, glad, sad, excited, relieved, sorry, proud, surprised, astonished, disappointed, ...
Usually the infinitive gives the cause of the emotion:
Maggie was surprised to win.
Adjectives of capability, readiness, and willingness:
e.g. ready, able, eager, prepared, reluctant, willing, unable, unwilling, okay, set, afraid, embarrassed, frightened, ...
Usually the infinitive gives a potential future action:
Maggie was able to win.
Adjectives expressing an opinion:
e.g. kind, nice, good, sweet, wise, right, wrong, clever, smart, silly, generous, foolish, brave, stupid, unwise, mean, strong, ...
Usually the infinitive is a past action that is the reason for the speaker’s opinion:
Maggie was clever to win.
There are three different ways to structure an English sentence that uses an adjective to describe an infinitive verb:
Using "empty it" (common):
It is safe to drive this car.
With an infinitive subject (rare):
To drive this car is safe.
With the object first (common):
This car is safe to drive.
All three sentences above say that the action “drive this car” = safe. However, the three sentence structures follow slightly different rules and are used in slightly different contexts. Let’s have a look!
The most basic way to describe an infinitive verb with an adjective is to start the sentence with “empty it” (a pronoun with no meaning). Use this structure:
It
be
adjective
(of/for + subject)
infinitive
You can use sentences like this to describe an action in general:
It’s hard for students to say “squirrel” in English.
…or to describe a specific case when an action took place:
It was nice of you to come to my party.
You can introduce the subject of the infinitive action with of or for. Here is the difference:
of + subject → use it only when you are talking about a particular action.
for + subject → use it to talk about an action in general.
However, adding a subject for the infinitive is optional in both cases, and it is more common to hear these sentences without a subject:
It is safe to drive this car.
It is illegal to cross the street here.
It was easy to bake this cake.
It will be nice to visit mom next week.
When the adjective gives an opinion, we usually assume that the speaker is the subject of the infinitive. For example:
It was easy to bake this cake.
It will be nice to visit mom next week.
If you want to make it clear that this is someone else’s opinion, you’ll need to add some extra context. For example:
Apparently, it was easy to bake this cake.
According to John, it was easy to bake this cake.
More rarely, we will use an infinitive phrase as the subject of the sentence, instead of “empty it.” Sentences like this have this structure:
infinitive
be
adjective
(for + subject)
With an infinitive subject, we always use the form of the verb be (is, was, has been, ...). For example:
To drive this car is safe.
= It is safe to drive this car.
To say “squirrel” in English is hard for students.
= It is hard for students to say “squirrel” in English.
This sentence structure sounds old-fashioned or poetic. If you want to put the action first, it is much more common to use an English gerund phrase (with the -ing form of the verb) instead of an infinitive:
✅ Driving this car is safe.
✅ Saying “squirrel” in English is hard for students.
The other common case where we describe an infinitive action using an adjective is when the object of the infinitive is the subject of the sentence. Sentences like this have the structure:
subject
be
adjective
(of/for + subject)
infinitive
But notice that here, the subject of the sentence is the object of the infinitive verb. For example:
This car is easy to drive.
“Squirrel” is hard for students to pronounce.
This game is impossible to lose.
Even though the subject is the object of the infinitive, it is still the subject of the sentence, so you should still use subject pronouns:
✅ He is nice to talk to.
❌ Him is nice to talk to.
In these sentences, the adjective still describes the infinitive verb. However, in this case, you are saying the sentence to provide information about the object of the infinitive. Let’s compare:
It is easy to drive this car.
Driving the car = easy
This car is easy to drive.
This car has the feature: Driving it = easy
Let’s look at the other two sentences we saw above:
“Squirrel” is hard for students to pronounce in English.
This game is impossible to lose.
In each case, the adjective describes the whole action, but the sentence is about the object of the infinitive!
When you describe infinitive verbs with an adjective, you’ll use an adjective that describes an action, for example:
e.g. dangerous, important, good, easy, hard, simple, illegal, impossible, lovely, funny, ...
Grammarians call these kinds of adjectives “raising adjectives,” because they allow the infinitive or the object of the infinitive to be “raised” to become the subject of the sentence. Have a look at this list of common English raising adjectives for more examples!
Can you tell the difference between these two sentences?
Paul is prepared to learn.
Janice is easy to teach.
Here is the answer:
How do we know that Paul is the subject of the infinitive but Janice is the object of an infinitive?
The verb to teach is “missing” an object.
The adjective prepared always describes the subject and the adjective impossible is a raising adjective, so it always describes the object.
Usually these two rules combined will help you tell if the subject of the sentence should be the subject or the object of the infinitive verb. However, sometimes you will just need to use context.
In this post, we’ve looked at the two main ways to use English adjectives with infinitive verbs:
The infinitive adds information about the adjective (a.k.a. the infinitive is the “complement” of the adjective)
subject + be + adjective + infinitive
The adjective adds information about the infinitive (a.k.a. the adjective “describes” the infinitive)
it + be + adjective + (of/for + subject) + infinitive
infinitive + be + adjective + (of/for + subject)
subject + be + adjective + infinitive
Are you feeling prepared to learn more? Try our adjective + infinitive activities to practice what you’ve learned, or have a look at one of our other articles on the uses of infinitive verbs in English!
