Infinitive

Deciding when to use either a verb in the infinitive, present participle or as a gerund can be difficult. Look at these three sentences focused on the verb eat:

• Jack likes to eat at Tim’s house. (infinitive)
• Jack likes eating at Tim’s house. (gerund)
• Jack is eating at Tim’s house. (present participle)

This lesson will explain when and why to use the infinitive.

When to use the Infinitive

After certain verbs and combinations of helping and main verb:
forget, help, learn, teach, train, choose, expect, hope, need, offer, want, would like, agree, encourage, pretend, promise, allow, can/can’t afford, decide, manage, mean, refuse
Here are a few examples:

• I forgot to close the gap.
• Mary needs to leave now.
• Why are they encouraged to learn square dancing?
• We can’t afford to ignore your brother.

If there is an adjective you need to use the infinitive.

• She was pleased to see her last night.
• Tim is sad to leave you alone again.

If there is an adjective + enough you will use the infinitive:

• He was small enough to squeeze in the door.
• She is smart enough to work with him.

When To Use Ing Gerund

Gerunds are typically used in place of an infinitive. Be careful though since the verb with ing can also be a present participle. The easiest way to tell the difference is if it is acting like a noun.

• Smoking is an expensive habit. (gerund)
• Jack is smoking outside. (present participle)

The -ing form is used after a preposition and is almost always a gerund.

• She saw her before leaving Arizona.
• After working for so long it was time for sleep.

The only exception to this is when “to” is used as a preposition:

to as Preposition	Preposition
I am used	to	running.
I am used	to	leaving.
to as Infinitive	Infinitive
I used	to run.
I used	to leave.

You can also determine if you are going to use an infinitive or gerund is based on the words in front. There are certain words that are usually followed by a gerund: admit, appreciate, avoid, carry on, consider, defer, deny, detest, dislike, endure, enjoy, escape, excuse, face, feel like, finish, forgive, give up, can’t help, imagine, involve, leave off, mention, mind, postpone, practice, put off, report, resent, risk, can’t stand, suggest
Here are a few examples:

• She enjoys talking with her mom.
• Tim really detests eating at Jack’s.
• I feel like walking the dog.

Be careful since there are some words that can be followed by an infinitive or gerund. Some of these words include: allow, advise, begin, continue, hate, intend, like, love, permit, prefer, propose, start, stop, urge

• She prefers to sing with Timmy.
• She prefers singing with Timmy.
• He stopped to help his mom.
• He stopped helping his mom.

Be careful since there are times when using the infinitive or gerund can change the meaning of the sentence. In the first two examples the sentences take on the same meaning. In the last two there is a difference between “stopped to help” and “stopped helping”.