Infinitives
B1 · IntermediateGerunds & InfinitivesThe to-infinitive (to + base verb) shows purpose, follows adjectives like happy or ready, and completes verbs like want, decide, and hope.
What you'll learn
- To + base verb can express the purpose of an action — why someone did something
- Many common adjectives (happy, ready, hard, important...) are followed by a to-infinitive
- A large group of verbs (want, decide, hope, promise, agree, plan...) are always followed by a to-infinitive, never a gerund
- To only ever appears once — never double it with 'for to'
To + the base form of a verb
A to-infinitive is 'to' followed by the base form of a verb: to ask, to buy, to help. It shows up after certain verbs and adjectives, and it can explain the purpose of an action.
Infinitive of purpose
To + verb can answer the question 'why?' — it explains the reason or goal behind an action, without needing the word 'for'.
Infinitive after an adjective
Many common adjectives that describe feelings or judgments (happy, ready, glad, hard, difficult, important, easy) are followed by a to-infinitive.
Infinitive after certain verbs
A large group of verbs — want, decide, hope, promise, agree, plan, offer, manage, refuse, afford — are always followed by a to-infinitive, never the -ing form.
Real English
Watch out
The infinitive of purpose is just 'to + verb' — never add 'for' in front of it.
Decide, like want, hope, and promise, is always followed by a to-infinitive — never the -ing form.
After an adjective like happy, ready, or hard, use the to-infinitive, not the gerund.
Real life — Planning a trip
"Why are you saving so much money?"
"I'm saving to buy a new laptop before the trip."
"Makes sense. I need to book my flight soon too."
"Me too — I want to get a good deal."
Practice
Exercise 1 · Choose the correct sentence
Choose the correct sentence — infinitive of purpose.
Exercise 2 · Choose the correct sentence
Choose the correct sentence — infinitive of purpose.
Exercise 3 · Choose the correct sentence
Choose the correct sentence — infinitive after an adjective.
Exercise 4 · Choose the correct sentence
Choose the correct sentence — want always takes a to-infinitive.
Exercise 5 · Choose the correct sentence
Choose the correct sentence — decide always takes a to-infinitive.
Exercise 6 · Choose the correct sentence
Choose the correct sentence — infinitive after an adjective.
Exercise 7 · Choose the correct sentence
Choose the correct sentence — promise always takes a to-infinitive.
Exercise 8 · Choose the correct sentence
Choose the correct sentence — infinitive of purpose after a noun.
Exercise 9 · Complete the sentence
Complete with a to-infinitive: 'She hopes ___ (pass) the exam.'
Exercise 10 · Complete the sentence
Complete with a to-infinitive of purpose: 'I saved money ___ (buy) a new laptop.'
Exercise 11 · Sort into groups
0 / 6 sorted
Quick challenge
Five quick questions to check what stuck.
Question 1 / 5
Score: 0/0
Choose the correct sentence.
You learned
- A to-infinitive is 'to' + the base form of a verb.
- It can express the purpose of an action, without needing 'for'.
- It follows many common adjectives (happy, ready, hard, important...).
- A large group of verbs (want, decide, hope, promise...) are always followed by a to-infinitive.
Related grammar lessons
Gerunds
Learn how the -ing form works as a noun — as a subject, as the object of a verb, and after prepositions.
Verb Patterns
Learn the three groups of English verbs — gerund only, infinitive only, and verbs that allow both — and how to tell them apart.
Verb + Object + Infinitive
Learn the pattern verb + person + to-infinitive, used with want, ask, tell, advise, and many other verbs.
Bare Infinitive
Learn when the infinitive drops 'to' — after modal verbs, after let and make, and in a few fixed expressions.