There are three verb forms: the to-infinitive, gerunds and participles.
The to-infinitive
1.- The to-infinitive form is the base form of the verb: to + verb.
To look.
To wash.
To cook.
What is the to-infinitive used for?
1-After some verbs: afford, agree, appear, beg, care, choose, claim, consent, decide, demand, expect, forget, have, hope, hear, learn, listen, offer, plan, prepare, promise, refuse, regret, see, smell, etc.
I decided to go to the party.
2-To express purpose.
She saved money to buy the hat she wanted.
3-After adjectives: afraid, anxious, careful, clever, eager, fortunate, glad, happy, lucky, proud, reluctant, sad, willing, etc.
He was willing to accept your offer.
4-After question words (what, who, what, where, when).
I never know what to wear.
5-After want, would like, would prefer, would love.
I would prefer to eat outside today.
6-After a noun or a pronoun.
We need your approval to continue with the project.
7-After the following structure: it + linking verb + adjective.
It is important to work together.
8-After too and enough.
I’m too tired to play with you.
She is smart enough to solve the problem.
Gerunds -ing form
2.- Gerunds are other verb forms that are words that end in –ing that functions as nouns.
What is the gerund -ing form used for?
1-We use gerunds after the verbs: admit, appreciate, avoid, allow, begin, confess, consider, deny, discuss, dislike, enjoy, fancy, finish, forget, go, hate, keep, imagine, include, keep, like, love, lose, mind, miss, quit, save, suggest, permit, practise, prevent, prefer, recall, regret, quit, recommend, save, start, suggest, stop, spend, waste.
*Verbs that express likes, dislikes and preferences.
I always avoid touching the old box.
I don’t recall telling you that.
We enjoy studying at the library.
2-We can use gerunds as the subject of a sentence.
Cooking is my favourite part of the day.
Dancing requires a lot of effort.
Running gives him energy.
3-We can use gerunds as the direct object of a sentence.
He admitted telling the truth.
I remember visiting that park as a child.
We don’t mind taking a break.
4-We can use gerunds as the subject complement of a sentence.
Their main goal is achieving success.
One of the benefits of the school curriculum is learning a second language.
Her greatest pleasure is teaching English.
5-We can use gerunds after prepositions.
I’m not good at playing the drums.
My dogs are excited about going to the park.
Brian is afraid of speaking in public.
6-We can use gerunds after the expressions: it’s no use, can’t help, to be worth, what’s the use of, can’t stand, to be fed up with.
I can’t stand being ignored by my coworkers.
It’s no use fixing the car.
They’re fed up with listening the neighbours’ music.
7-We can use gerunds after phrasal verbs.
They ended up buying the air conditioner.
Jess has given up smoking.
8-We can use gerunds after other common phrasal verbs with the preposition ‘to’: look forward to, to be used to, to be accustomed to, in addition to, to take to, object to, to get around to.
In addition to having a well-paid job, she also has her own restaurant.
9-After the structure adjective + preposition.
I’m sad about having to go.
Jade is interested in learning a second language.
He is responsible for taking care of his grandparents.
Participles
3.- Participles are verb forms used as adjectives that modify nouns; there are three types of participles: present participles, past participles and perfect participles.
Present participles end in -ing.
What are the present participles used for?
1-We can use the present participles in continuous verb tenses (present continuous/progressive tense, past continuous/progressive tense, future continuous/progressive tense).
Mel is running.
Mel was running.
Mel will be running.
2-We can use the present participles as adjectives.
The chirping birds.
3-We can use the present participles as gerunds.
Smoking is prohibited in this shop.
Past Participles
Past participles end in -ed for regular verbs, but irregular verb have different endings.
What are the past participles used for?
1-We can use the past participles in perfect tenses (present perfect tense, past perfect tense, future perfect tense).
I have already sent the email.
They had turned off the lights by 10 o’clock.
The meeting will have finished by 3 o’clock.
2-We can use the past participles as adjectives.
We noticed a frozen lake next to the forest.
3-We can use the past participles in passive forms.
The damaged bike was fixed.
4-We can use the past participles in the causative.
I had my hair dyed.
Perfect Participles
We use the perfect participles to show an action that happened before another action or at a certain time in the past; we can also use them in the active and the passive.
Active (having + past participle)
Having finished the project, Louis went to sleep.
Passive (having been + past participle)
Having been fed, the dog played with its toys.
4-Finite verbs have a subject, a tense, a number and person. To identify them, make sure to find the subject and the tense.
She washed her face. (she = subject, washed = finite verb)
I am brushing my hair. (I = subject, am = finite verb)
5-Non-finite verbs do not have a subject, a tense, a number and person. There are three types of non-finite verbs: infinitive, participles and gerunds.
Infinitive: they love to travel.
Participles:
Present: Nina is driving.
Past: Nina has reached her destination.
Gerund: reading is my favourite hobbie.
More information about verbs here.