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O Level English · Grammar & Verb Forms

Gerunds, Participles & Infinitives: Understanding Non-Finite Verb Forms

A comprehensive guide to gerunds, participles and infinitives, with clear explanations, many examples, common mistakes, comparisons, practice and an O Level-style self-check.

EDUSAMBAM Editorial Team|Grammar & Verb Forms|English Language
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Article purpose: English verbs do more than show actions. Verb forms can also function as nouns, adjectives and parts of larger verb structures. Three forms that often confuse learners are the gerund, the participle and the infinitive. This article teaches you how to recognise them, understand their jobs in sentences, choose between them accurately and avoid common errors.

1. The Big Picture

A useful starting point is to remember that these forms come from verbs, but they do not all behave like ordinary finite verbs.

EDUSAMBAM principle

GERUND → verb form working as a noun
PARTICIPLE → verb form working mainly as an adjective or as part of a verb phrase
INFINITIVE → to + base verb, or sometimes the bare base verb after a special verb pattern

Compare:

2. What Is a Gerund?

A gerund is the -ing form of a verb used as a noun. It can therefore perform jobs normally performed by nouns.

Examples

Reading improves vocabulary.
Reading is the subject.

I enjoy reading.
reading is the object of enjoy.

Her favourite activity is reading.
reading completes the sentence after is.

3. Gerunds as Subjects

A gerund can begin a sentence and act as its subject.

In each sentence, the -ing word names an activity. That is why it is functioning as a noun.

4. Gerunds as Objects

Many verbs are followed naturally by a gerund.

Common patterns

enjoy reading   •   avoid arguing   •   finish writing   •   consider moving   •   suggest waiting

Important: do not assume that every verb takes a gerund. Verb patterns must be learned with the verbs that govern them.

5. Gerunds After Prepositions

When a verb follows a preposition, it normally takes the -ing form, not to + base verb.

Common trap

Incorrect: interested in to learn
Correct: interested in learning

6. The Important “to” Trap

The word to does not always introduce an infinitive. Sometimes it is a preposition, and a gerund follows it.

But:

7. What Is a Participle?

A participle is a verb form that can help form a verb phrase or can function adjectivally to describe a noun or pronoun. The two major participles are the present participle and the past participle.

Remember

Present participle: usually the -ing form → running, singing, breaking, smiling.

Past participle: often an -ed form for regular verbs, but irregular verbs have many different forms → walked, broken, written, taken, seen.

8. Present Participles

The present participle ends in -ing, but an -ing word is not automatically a gerund. Its job in the sentence decides the classification.

Compare the same form

Swimming is enjoyable. → noun function → gerund.

The swimming child waved. → describes a noun → present participle.

The child is swimming. → part of the verb phrase → present participle.

This is one of the most important distinctions in the whole topic: form alone is not enough; function matters.

9. Present Participles as Adjectives

A present participle can describe a person, animal, object or situation.

In an exciting match, exciting describes the match. It is not the subject or object of the sentence; it is functioning adjectivally.

10. Participles in Verb Phrases

Participles also combine with auxiliary verbs to form verb phrases.

Here, reading, waiting, finished, written and forgotten are participial forms within larger verb phrases.

11. Past Participles

Past participles are especially important in perfect and passive constructions, and they can also act as adjectives.

Regular vs irregular

Regular: work → worked → worked; finish → finished → finished.

Irregular: write → wrote → written; break → broke → broken; take → took → taken.

12. Participles vs Gerunds: The Key Test

When you see an -ing word, ask: What job is it doing?

Three quick tests

1. Is it naming an activity? → likely a gerund.
2. Is it describing a noun? → likely a participle.
3. Is it helping an auxiliary verb form the verb phrase? → present participle.

Compare:

13. What Is an Infinitive?

The most familiar infinitive is to + base form of the verb.

Examples in sentences:

14. Infinitives of Purpose

An infinitive can explain why an action is performed.

Purpose test

Ask: Why did he/she/they do it? If the answer is an intended purpose, an infinitive is often appropriate.

15. Infinitives After Verbs

Many common verbs are followed by an infinitive.

Examples

want to learn • decide to leave • hope to succeed • plan to study • promise to help • agree to wait • refuse to answer • manage to finish

16. Bare Infinitives

A bare infinitive is the base verb without to. It occurs in several important patterns.

Common error

Incorrect: She can to swim.
Correct: She can swim.

17. Gerund or Infinitive?

Some verbs can take a gerund, some take an infinitive, and some can take either with a change or no major change in meaning. This is an area where learners should study common patterns rather than rely on one universal rule.

PatternExample
enjoy + -ingI enjoy reading.
avoid + -ingHe avoided answering.
want + to + verbI want to learn.
decide + to + verbShe decided to leave.
suggest + -ingThey suggested waiting.
hope + to + verbWe hope to succeed.

18. Verbs Where Meaning Can Change

Some verbs can be followed by either form, but the meaning may change.

Remember / forget

I remember locking the door. → I have a memory of a past action.

Remember to lock the door. → Do not forget the action that you need to perform.

I forgot meeting him. → I did meet him, but I do not remember it.

I forgot to meet him. → I failed to perform the planned action.

Stop

He stopped smoking. → He ended the activity.

He stopped to smoke. → He stopped another activity in order to smoke.

19. Meaning Can Change with “Try”

The distinction is subtle but important. Always read the whole sentence before deciding what the form means.

20. Participial Phrases

A participial phrase contains a participle and other words connected to it. It can add information about a noun or describe an action or circumstance.

Examples

Walking through the forest, Maya heard a strange sound.

Exhausted after the journey, the travellers rested.

Having finished the experiment, the students recorded their results.

Shocked by the news, he remained silent.

The opening phrase should normally connect logically to the subject that follows. A mismatch can create a dangling participle.

21. Avoiding Dangling Participles

Compare:

Incorrect and improved

Walking down the road, the rain began.
The sentence appears to say that the rain was walking.

Walking down the road, I was caught in the rain.

The participial phrase Walking down the road needs a sensible person or thing to modify.

22. Infinitive Phrases

An infinitive can be expanded into a phrase containing its object or other modifiers.

Examples:

23. A Simple Identification Method

Five-step method

STEP 1: Find the verb form.
STEP 2: Ask what form it has: -ing, past participle, or to + base verb?
STEP 3: Ask what job it performs.
STEP 4: Check the word immediately around it and the whole sentence.
STEP 5: Explain the meaning, not just the label.

24. Worked Analysis: “Reading”

Look at the word reading in four sentences.

  1. Reading before bed helps me relax. → gerund; it names the activity and is the subject.
  2. I enjoy reading before bed. → gerund; it is the object of enjoy.
  3. The reading child ignored the noise. → present participle; it describes the child.
  4. The child is reading. → present participle; it forms part of the verb phrase.

Lesson: the spelling is identical, but the grammatical function changes.

25. Worked Analysis: “Broken”

The same form can therefore participate in a verb construction or describe a noun, depending on context.

26. Worked Analysis: “To Read”

27. Common Errors

28. Gerund, Participle or Infinitive? Quick Comparison

Form / useMain jobExample
GerundActs as a nounSwimming is fun.
Present participleDescribes or helps form a verb phraseThe swimming boy waved. / He is swimming.
Past participleHelps form perfect/passive constructions or describesShe has finished. / the broken chair
Infinitiveto + base verb; often expresses intention, purpose or complements a verbI want to learn.
Bare infinitiveBase verb in special patternsShe can learn.

29. Examination and Writing Advice

When an examination question tests grammar, sentence transformation or accuracy, do not choose a form simply because it “sounds familiar”. Check the verb pattern, preposition, meaning and grammatical function.

Strong editing routine

Verb pattern → surrounding word → sentence meaning → grammatical function → final check.

30. Guided Practice

Identify the bold form and explain its function.

  1. Swimming every morning keeps him fit.
  2. The swimming instructor called the children back.
  3. She is swimming across the pool.
  4. They decided to postpone the meeting.
  5. He apologised for arriving late.
  6. The broken glass was carefully removed.
  7. The glass was broken during the storm.
  8. We went to the library to research the topic.
Suggested answers

1. Gerund — subject. 2. Present participle — describes instructor. 3. Present participle — part of the verb phrase. 4. Infinitive — complement of decided. 5. Gerund — object of the preposition for. 6. Past participle — adjectival description. 7. Past participle — part of a passive construction. 8. Infinitive — expresses purpose.

31. Mastery Checklist

32. Final Memory Map

Remember this

GERUND = -ING FORM DOING A NOUN'S JOB

PRESENT PARTICIPLE = -ING FORM DESCRIBING OR HELPING A VERB PHRASE

PAST PARTICIPLE = PARTICIPLE FORM USED IN PERFECT/PASSIVE STRUCTURES OR AS A DESCRIPTION

INFINITIVE = TO + BASE VERB

BARE INFINITIVE = BASE VERB WITHOUT TO IN SPECIAL PATTERNS

33. Quick Assessment

Answer every question. Select one answer for each question. Your score is shown after submission.
0 of 15 answered
0/15
1.Which sentence contains a gerund?
2.What makes “swimming” a gerund in “Swimming is healthy”?
3.Which sentence contains a present participle describing a noun?
4.Which is an infinitive?
5.Which form normally follows a preposition such as “in” or “for” when it is a verb?
6.Which sentence is correct?
7.Which sentence contains a bare infinitive?
8.What is wrong with “Walking down the road, the rain began”?
9.Which sentence uses an infinitive to express purpose?
10.Which pair shows a change in meaning?
11.In “The broken window was replaced”, what is “broken” doing?
12.Which sentence correctly uses “look forward to”?
13.Which statement best explains the difference between a gerund and a participle?
14.Which sentence is correct?
15.What is the best first question when classifying an “-ing” word?
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