Infinitives (To-infinitive & Bare Infinitive)

The infinitive is the base form of a verb, used either with "to" (to-infinitive or full infinitive) or without it (bare infinitive). This essential A2–B2 lesson covers everything you need to master infinitives in English. To use infinitives correctly, you need to understand 2 Forms and 4 Main Zones:

• Form 1: To-infinitive (full infinitive) — used after most verbs, adjectives, and for purpose
• Form 2: Bare infinitive (without 'to') — used after make/let, perception verbs, and modals
• Zone 1: Verbs followed by to-infinitives (want, decide, hope, plan, agree...)
• Zone 2: Adjectives, too/enough, and question words + to-infinitives
• Zone 3: Bare infinitive patterns (make, let, help, perception verbs, had better, would rather)
• Zone 4: Advanced infinitive forms (perfect, passive, continuous infinitives)

The biggest challenge? Understanding when to use to-infinitive vs bare infinitive, and distinguishing infinitives from gerunds. For detailed gerund patterns and usage, see Gerunds.

Don't confuse infinitives with gerunds:

• After prepositions, always use gerund, NOT infinitive: "good at playing" ✓ (NOT "good at to play" ❌)
• After certain verbs, use infinitive: "want to go" ✓ (NOT "want going" ❌)
• For detailed gerund patterns, see Gerunds.

This lesson focuses on infinitive patterns and usage. Let's master the two forms across four key zones.

To-infinitive Basics: Verbs Followed by Infinitives

The to-infinitive (also called full infinitive) is the most common infinitive form in English. It consists of "to" + base verb (to go, to eat, to study). Many verbs are always followed by a to-infinitive, never a gerund.

Verbs Always Followed by To-infinitive

Here are the most common verbs that require a to-infinitive:

Examples:

• She decided to study abroad next year.
• I can't afford to buy a new laptop right now.
• He agreed to help me with the project.
• We plan to travel to France next summer.
• She refused to open the door for the stranger.
• I want to be a doctor when I grow up.

It is + Adjective + To-infinitive

The to-infinitive is commonly used in the pattern "It is + adjective + to-infinitive". This structure is used to make general statements about actions:

More examples:

• It is difficult to learn a foreign language as an adult.
• It is not easy to live in a big city on a small salary.
• It was nice to hear from you after so many years.

The subject "It" is a placeholder. The real subject is the to-infinitive phrase.

⚠️ The Suggest/Advise Trap

This is a major error zone. Verbs like suggest, recommend, and consider are frequently confused with verbs like advise, tell, and ask because they seem similar. However, their patterns are completely different.

Pattern A: Suggest, Recommend, Consider (NO object + to-infinitive)

These verbs cannot be followed by "object + to-infinitive". Instead, they take:

• Gerund: suggest/recommend/consider + doing
• That-clause: suggest/recommend that + subject + verb

Pattern B: Advise, Tell, Ask, Want (CAN use object + to-infinitive)

These verbs can be followed by "object + to-infinitive":

The key difference:

• suggest/recommend = NO object + to-infinitive (use gerund or that-clause instead)
• advise/tell/ask/want = YES object + to-infinitive ✓

👉 Practice To-infinitive Basics →

To-infinitive with Adjectives, Too & Enough

The to-infinitive is used in several important patterns with adjectives, including too and enough patterns. Let's explore four key structures.

Adjective + To-infinitive (Feelings & States)

After adjectives describing feelings, willingness, probability, use a to-infinitive:

More examples:

• She was surprised to see him at the airport.
• I'm pleased to meet you. My name is David.
• He was delighted to receive an award for his work.
• They are willing to work extra hours to finish the project.

Too + Adjective + To-infinitive

The pattern "too + adjective + to-infinitive" means "so much that it is not possible". It expresses that something is excessive and prevents an action:

Examples:

• The box was too heavy to lift without help.
• The water is too cold to swim in today.
• The coffee is too hot to drink. Please wait a moment.
• He is too young to drive a car in this country.

Adjective + Enough + To-infinitive

The pattern "adjective + enough + to-infinitive" means "sufficiently". It expresses that something has reached the necessary level:

Note the word order: The adjective comes BEFORE "enough", not after.

• ✅ old enough to drive
• ❌ enough old to drive

Examples:

• He is old enough to live on his own now.
• This suitcase is light enough to carry with one hand.
• She is clever enough to solve the puzzle in five minutes.

Question Word + To-infinitive

After question words (what, how, where, when, which), use a to-infinitive to express indirect questions:

This structure is very common in everyday English and is simpler than using a full question clause.

👉 Practice Adjectives, Too & Enough →

Verb + Object + To-infinitive & Infinitive of Purpose

This section covers two important infinitive patterns: adding an object between the verb and infinitive, and using infinitives to express purpose.

Verb + Object + To-infinitive Pattern

Many verbs follow the pattern "verb + object + to-infinitive", where you tell, ask, or want someone to do something:

Note: This pattern is also used in reported commands and requests. For more on this, see Reported Commands & Requests.

⚠️ Disambiguation: Advise vs Suggest (Revisited)

Remember the key difference from earlier:

Making Infinitives Negative

To make a to-infinitive negative, put "not" before "to". The word order is critical:

Examples:

• She was warned not to walk alone at night in that area.
• She promised not to complain about the problem again.
• I told him not to be late for the interview.

The pattern is always: not to + base verb

Infinitive of Purpose

The infinitive of purpose explains why someone does something. It answers the question "Why?" or "For what purpose?"

"in order to" and "so as to" are more formal than the simple "to", but they mean exactly the same thing.

Examples:

• She went to the supermarket to buy some vegetables for dinner.
• We left early in order to avoid the heavy traffic.
• He exercises every morning in order to stay healthy.
• He went to the library to study for his research paper.

Negative Purpose: In Order Not To / So As Not To

To express negative purpose (to prevent something from happening), use:

• in order not to + base verb
• so as not to + base verb

You cannot use the simple "to" for negative purpose.

Examples:

• She put on a warm coat so as not to catch a cold.
• She took a taxi in order not to be late for her interview.

Common mistakes:

• ❌ "for to avoid" — never use "for to"
• ❌ "for avoiding" — "for" takes a noun or gerund, NOT used for purpose in this way
• ✅ "to avoid" or "in order to avoid"

👉 Practice Verb + Object + Infinitive & Purpose →

Bare Infinitive: Make, Let, Help & More

⚠️ IMPORTANT SHIFT: Up to this point, all infinitives have used "to". This chapter introduces the bare infinitive (infinitive without "to"). This is the #1 source of infinitive errors because learners overgeneralize the "to-infinitive" pattern.

The bare infinitive is the base form of the verb without "to". It is used after specific verbs and expressions. You must memorize which verbs take bare infinitive.

⚠️ The Make/Let Trap — Error Zone #1

This is the most common infinitive mistake. After make and let + object, you MUST use a bare infinitive (without "to").

Why learners make this mistake: Most English infinitives use "to" (want to go, decide to stay, etc.), so learners assume ALL infinitives need "to". But make and let are exceptions.

Make + Object + Bare Infinitive

"Make" means to force or cause someone to do something:

More examples:

• The loud noise made everyone look around in surprise.
• The comedian always makes the audience laugh.

Note: In the passive voice, make is followed by a to-infinitive:

• Active: The teacher made the students do the exercise.
• Passive: The students were made to do the exercise.

Let + Object + Bare Infinitive

"Let" means to allow or permit someone to do something:

More examples:

• They wouldn't let us take photos inside the museum.
• Her parents let her have a pet when she turned ten.
• Don't let the children play near the swimming pool unsupervised.

Help: The Exception

Help is unique because it can be followed by either a bare infinitive or a to-infinitive. Both are correct:

Both forms are acceptable in modern English. The bare infinitive is slightly more common in informal speech.

Important: Make and let do NOT have this flexibility:

• make + bare infinitive ONLY ✓ (NOT make to do ❌)
• let + bare infinitive ONLY ✓ (NOT let to do ❌)
• help + bare infinitive OR to-infinitive ✓ (both OK)

Perception Verbs + Bare Infinitive

Perception verbs (verbs about seeing, hearing, or sensing) are followed by object + bare infinitive when describing a complete action that you witnessed:

Examples:

• Did you hear someone call your name just now?
• I watched the children play in the park all afternoon.
• She noticed a spider crawl across the ceiling.
• We felt the ground shake during the earthquake.

Note: These verbs can also be followed by -ing (present participle) to emphasize an action in progress, but that's a different structure (e.g., "I saw him leaving" = I saw him in the process of leaving).

Had Better / Would Rather + Bare Infinitive

Two common expressions use the bare infinitive:

Had Better + Bare Infinitive (Strong Advice/Urgency)

"Had better" expresses strong advice or warning. It is followed by a bare infinitive:

Negative: had better not + bare infinitive

• You'd better not be late for the interview tomorrow.

Would Rather + Bare Infinitive (Preference)

"Would rather" expresses preference. It is followed by a bare infinitive:

Negative: would rather not + bare infinitive

• I'd rather not talk about it, if you don't mind.

Examples:

• I'd rather stay at home tonight than go to the restaurant.
• He would rather read a book than watch TV.
• I'd rather not talk about it, if you don't mind.

👉 Practice Bare Infinitive →

Advanced Infinitives: Perfect, Passive & Continuous

Advanced infinitive forms express time relationships (perfect), voice (passive), and aspect (continuous). These B2-level structures are used in formal and written English.

Perfect Infinitive: To Have + Past Participle

The perfect infinitive (to have + past participle) emphasizes that the infinitive action happened before the main verb. It shows a time relationship.

When to use perfect infinitive:

Use the perfect infinitive after verbs like seem, appear, claim, report, believe when referring to an event that clearly happened before the present moment:

Examples:

• She seems to have lost a lot of weight since we last saw her.
  • (She lost weight in the past → It appears now)
• He claimed to have met the celebrity several years before.
  • (He met her in the past → He claims this now)
• He is believed to have left the country last week.
  • (He left last week → People believe this now)
• He is reported to have donated a large sum of money to charity last month.
  • (He donated last month → Reports say this now)

Perfect infinitive vs simple infinitive:

• She seems to lose weight. (Seems unusual — suggests ongoing or future)
• She seems to have lost weight. (Past action — she already lost it)

Passive Infinitive: To Be + Past Participle

The passive infinitive (to be + past participle) is used when the subject receives the action rather than performing it:

When to use passive infinitive:

Use the passive infinitive when the focus is on what happens to the subject, not who does the action:

Examples:

• The report needs to be completed before the end of the day.
  • (Someone needs to complete the report)
• The homework was expected to be completed before class starts.
  • (Someone should complete the homework)
• The package appears to have been damaged during transit.
  • (Someone damaged the package)

Continuous Infinitive: To Be + -ing

The continuous infinitive (to be + -ing) is used after verbs like seem, appear to describe an action in progress right now:

When to use continuous infinitive:

Use the continuous infinitive when you want to emphasize that an action is happening at this moment:

Examples:

• He appears to be working on a difficult project at the moment.
  • (It looks like he is working now)
• He appears to be talking on the phone. I'll come back later.
  • (It looks like he is talking now)
• They seem to be painting the house. I can smell fresh paint.
  • (It seems they are painting now)
• The missing child is thought to be hiding somewhere in the city.
  • (People think the child is currently hiding)

Perfect Passive Infinitive: To Have Been + Past Participle

The perfect passive infinitive combines both perfect and passive forms. Use it when:

1. The action happened before the main verb (perfect)
2. The subject received the action (passive)

Examples:

• The building is said to have been built in the 18th century.
  • (Someone built it long ago → People say this now)
• The letter was supposed to have been delivered yesterday, but there was a delay.
  • (Someone should have delivered it yesterday, but didn't)
• The money is believed to have been hidden in a secret bank account.
  • (Someone hid the money → People believe this now)
• The painting is believed to have been painted over 500 years ago.
  • (Someone painted it long ago → People believe this now)
• She was glad to have been chosen for the opportunity to present her research.
  • (Someone chose her → She was glad about this)

Making Advanced Infinitives Negative

For perfect, passive, and continuous infinitives, put "not" before the entire infinitive form:

Examples:

• She regrets not having studied harder in college.
  • (She didn't study hard → She regrets this now)
• He was angry about not being promoted.
  • (He wasn't promoted → He was angry about this)
• She claims not to have played any part in the fraud.
  • (She says she didn't participate)

👉 Practice Advanced Infinitives →

Common Mistakes to Avoid

Quick Summary

The 2 Forms Decision Tree

Step 1: Identify the verb or expression before the infinitive

Step 2: Is it make, let, or a perception verb (see/hear/watch/feel/notice)? → YES: Use bare infinitive (without "to") → NO: Go to Step 3

Step 3: Is it "had better" or "would rather"? → YES: Use bare infinitive (without "to") → NO: Use to-infinitive

Verbs Followed by To-infinitive (Common Ones)

Verbs + Object + To-infinitive

Remember: suggest and recommend do NOT use this pattern (use gerund or that-clause instead)

Bare Infinitive After

Infinitive of Purpose: Quick Flow

Step 1: Ask "Why did they do X?" Step 2: If answer is a purpose → use infinitive Step 3: Structure: to + base verb OR in order to OR so as to Step 4: Negative purpose: in order not to OR so as not to (NOT simple "to not")

Formation of Advanced Infinitives

Practice Tips

1. Master the bare infinitive first: The make/let trap is the #1 error. Memorize: make/let + object + NO 'to'. Practice until it becomes automatic.

2. Create verb lists: Make your own list of verbs that take to-infinitives (want, decide, hope, plan, agree, promise...) and test yourself regularly. Use them in sentences daily.

3. Spot suggest/advise differences: Remember the key rule — suggest takes gerund or that-clause (suggest doing / suggest that...), while advise takes object + to-infinitive (advise someone to do). Never confuse them.

4. Practice negative infinitives: Always "not to" do, never "to not do" or "don't do". The word order is critical and non-negotiable.

5. Advanced forms need context: Perfect infinitive (to have done) shows the action happened before the main verb. Passive infinitive (to be done) shows the subject receives the action. Continuous infinitive (to be doing) shows action in progress. Focus on understanding why you'd use each form, not just memorizing patterns.

Practice All Exercises

Ready to master infinitives? These comprehensive infinitive exercises include multiple choice and worksheet practice with answers. Available online for free, these exercises progress from basic A2 patterns to advanced B2 forms. For comparison with gerunds, see our gerund exercises. Work through the sets below in order:

👉 Start with Set 5: Advanced Infinitives for a comprehensive challenge covering all infinitive forms and usage patterns!