There are 9 parts of speech or word classes in English language:
– nouns
– pronouns
– determiners
– verbs
– prepositions
– adjectives
– adverbs
– conjunctions
– interjections

Gerunds are -ing forms that function as nouns.
– I love cooking.
cooking = gerund

Infinitives are “to + base forms” that function as nouns.
– My father asked me to wait.
to wait = infinitive

1. Let us compare “I love cooking” with “I love that book”
‘That book’ is a noun phrase (a phrase that functions as a noun)
‘Cooking’ has the same grammatical function as ‘that book’ (as a noun).

2. Let us compare ‘My father asked me to wait’ with ‘My father asked me a question’
‘A question’ is a noun phrase.
‘To wait’ has the same grammatical function as ‘a question’ (as a noun)

We need to study gerunds and infinitives because:
1. There are verbs that can only be followed by gerunds
I enjoy going to the movies. (correct)
I enjoy to go to the movies. (wrong)

2. There are verbs that can only be followed by infinitives
Jason wants to visit a museum on Friday. (correct)
Jason wants visiting a museum on Friday. (wrong)

3. There are verbs that can be both followed by gerunds and infinitives
Tony likes eating Japanese food. (correct)
Tony likes to eat Japanese food at that restaurant. (correct)

1. Gerunds as subject.
– Jogging is a hobby of mine. (jogging = subject)
– Driving fast can be dangerous. (driving fast= subject)
– Looking after children needs patience. (looking after children= subject)

Gerund are equivalent to singular nouns.
Gerunds are used with singular verbs (is, was, -s forms)
Jogging is a hobby of mine. (correct)
Jogging are a hobby of mine. (wrong)

Looking after children needs patience. (correct)
Looking after children need patience. (wrong)

2. Gerunds as object.
– I enjoy reading. (reading = gerund)
– Daniel quit smoking a year ago. (smoking = gerund)
– He hates getting up early. (getting up = gerund)

3. Gerunds as subject complement.
A subject complement is a word or phrase that explains the sentence subject and is usually after a linking verb (is,am,are,was,were,been,being,feel, seem, etc.)

– Her hobby is swimming.
swimming = gerund
is = linking verb
– My goal is winning that competition.
winning = gerund
is = linking verb

4. Gerunds as object of preposition.
Prepositions can only be followed by nouns or gerunds.
– I am interested in collecting stamps. (in = preposition)
– Thank you for inviting me. (for = preposition)
– After talking to him, I went home. (after = preposition)

5. Gerunds after certain verbs.
– He started learning English three months ago. (start + gerund)
– She stopped calling him. (stop + gerund)
– I finished reading that book last week. (finish + gerund)

6. Gerunds after certain phrasal verbs.
– When will you give up smoking? (give up + gerund)
– He kept on asking for money. (keep on + gerund)
– Jim ended up buying a new TV after his old one broke. (end up + gerund)

7. Gerunds after phrasal verbs ending with ‘to.’
– I look forward to hearing from you soon.
(look forward to + gerund)
– I am used to waiting for buses.
(be used to + gerund)
– When will you get around to mowing the grass?
(get around to + gerund)

be used to + gerund
be accustomed to + gerund
be averse to + gerund
confess to + gerund
get used to + gerund
get around to + gerund
look forward to + gerund
object to + gerund
take to + gerund

8. Gerunds after certain phrases.
can’t help + gerund
She couldn’t help falling in love with him.

can’t stand + gerund
I can’t stand being stuck in traffic jams.

it’s no use + gerund
It’s no use trying to escape.

there’s no point in + gerund
There’s no point in wasting time.

1. Infinitives as subject.
– To win the competition is our goal.
(to win = subject)
– To play soccer for the national team is his dream.
(to play = subject)
– To travel around the world requires a lot of time and money.
(to travel = subject)

2. Infinitives as object (after verbs).
– Jim always forgets to eat.
(to eat = object, after the verb “forgets”)
– I want to learn a new language.
(to learn = object, after the verb “want”)
– We decided to visit my uncle.
(to visit = object, after the verb “decided”)

3. Infinitives as subject complement (after linking verb).
– My goal is to win that competition.
(to win = subject complement, is = linking verb)
– Her dream is to study overseas.
(to study = subject complement, is = linking verb)
– Our job was to handle the registration booth.
(to handle = subject complement, was = linking verb)

4. Infinitives after adjectives
– It’s very dangerous to cross a busy street.
(dangerous = adjective, to cross = infinitive)
– I was too tired to go to his party.
(tired = adjective, to go = infinitive)
– I’m happy to see you.
(happy= adjective, to see = infinitive)

5. Infinitives after phrases starting with question words.
– I don’t know what to say. (what + infinitive)
– She doesn’t know where to go. (where + infinitive)
– They knew how to solve that problem. (how + infinitive)

6. Infinitives after Verb + Object structure.
– I want you to help her.
(want + object + infinitive)
– My father told me to study hard.
(told + object + infinitive)
– They advised us to cancel the project.
(advised + object + infinitive)

He began to learn English when he was eight. (correct)
He began learning English when he was eight. (correct)

begin
– can be followed by both gerunds and infinitives
– there is no difference in meaning

start + gerunds
= start + infinitive

can’t bear + gerunds
= can’t bear + infinitive

can’t stand + gerunds
= can’t stand + infinitive

continue + gerunds
= continue + infinitive

hate + gerunds
= hate + infinitive

like + gerunds
= like + infinitive

love + gerunds
= love + infinitive

prefer+ gerunds
= prefer + infinitive

propose + gerunds
= propose + infinitive

He stopped smoking.
(= He doesn’t smoke anymore.)

He stopped to smoke.
(= He stopped doing an activity that he was doing at that time so that he could smoke.)

forget + gerund
not the same as forget + infinitive

go on + gerund
not the same as go on + infinitive

quit + gerund
not the same as quit + infinitive

regret + gerund
not the same as regret + infinitive

remember + gerund
not the same as remember + infinitive

stop + gerund
not the same as stop + infinitive

try + gerund
not the same as try + infinitive