eng9-3.4· Unit 3: Verbs & Tenses· ~13 min

Infinitive and gerund

When to use the -ing form and when to use to + verb

When one verb is followed by another, the second verb appears either as a gerund (the -ing form) or as an infinitive (to + verb), and the first verb decides which one. We use the gerund after certain verbs such as enjoy, finish, mind, avoid, suggest, keep, practise and miss, and always after a preposition (good at swimming, interested in learning, after leaving). A gerund can also act as the subject of a sentence (Swimming is good for you). We use the to-infinitive after verbs such as want, decide, hope, would like, promise, agree, plan, learn, need, offer and refuse, after many adjectives (happy to help, easy to do), and to express purpose (I went out to buy milk). After modal verbs and after make and let we use the bare infinitive with no 'to' (She let him go). Verbs like like, love, hate, start and begin can take either form with little change in meaning. For example: 'She enjoys reading, but today she wants to watch a film.'

Key terms

GerundThe -ing form of a verb used as a noun, for example 'reading' or 'swimming'.
To-infinitiveThe form 'to + verb', for example 'to read' or 'to swim'.
Bare infinitiveThe verb with no 'to', used after modal verbs and after make and let, for example 'She let him go'.
Gerund after a prepositionAfter any preposition we use the -ing form, for example 'good at swimming', 'interested in learning', 'before going'.
Gerund as subjectA gerund can be the subject of a sentence, for example 'Swimming is good for you'.
Infinitive of purposeThe to-infinitive used to answer 'why?', for example 'I went out to buy milk'.
Verb patterns: which form comes next
PatternVerbsExample
Verb + to-infinitivewant, decide, hope, would like, promise, agree, plan, learn, need, offer, refuseThey decided to buy a new house.
Verb + gerund (-ing)enjoy, finish, mind, avoid, suggest, keep, practise, can't help, missShe enjoys reading books.
Verb + bare infinitivemake, let (and after modal verbs)My parents let me go out.
Verb + either formlike, love, hate, start, beginShe likes reading / She likes to read.
When the gerund is forced
SituationRuleExample
After a prepositionUse the gerund (-ing), never the to-infinitiveShe is good at swimming.
After 'after', 'before', 'without', 'instead of'These are prepositions, so use the gerundBefore leaving the house, she locked the door.
As the subject of a sentenceUse the gerund, never 'to' + verbWalking is good for your health.
Choosing the form after a verb: 'She ___ (finish) her homework.'
  1. 1Find the first verb: The first verb is 'finish'. The form of the second verb depends on this verb.
  2. 2Check the pattern: 'finish' is in the gerund group (enjoy, finish, mind, avoid, suggest, keep, practise, can't help, miss).
  3. 3Apply the rule: After 'finish' we use the -ing form, not 'to do'.
  4. 4Answer: I have finished doing my homework.
Choosing the form after a verb: 'They ___ (agree) the contract.'
  1. 1Find the first verb: The first verb is 'agree', which decides the form that follows.
  2. 2Check the pattern: 'agree' is in the to-infinitive group (want, decide, hope, would like, promise, agree, plan, learn, need, offer, refuse).
  3. 3Apply the rule: After 'agree' we use 'to + verb', not the gerund 'signing'.
  4. 4Answer: They agreed to sign the contract.
🚫Common mistake

Do not use the to-infinitive after enjoy, finish, avoid, suggest, keep, mind or miss. Say 'enjoy reading' and 'avoid eating', not 'enjoy to read' or 'avoid to eat'.

🚫Common mistake

Do not use the gerund after want, decide, hope, plan, agree, promise or offer. Say 'want to learn' and 'decide to buy', not 'want learning' or 'decide buying'.

🚫Common mistake

After a preposition (at, in, of, about, before, after, without, instead of) always use the -ing form. Say 'good at swimming' and 'before leaving', never 'good at to swim' or 'before to leave'.

⚠️Caution

After make and let, and after modal verbs, drop the 'to'. Say 'She let him go' and 'The teacher made us wait', not 'let him to go' or 'made us to wait'.

Rules

  1. 1Use the gerund (-ing) after these verbs: enjoy, finish, mind, avoid, suggest, keep, practise, can't help, miss.
  2. 2Always use the gerund after a preposition (good at drawing, interested in cooking, before going) and when the verb is the subject (Swimming is healthy).
  3. 3Use the to-infinitive after these verbs: want, decide, hope, would like, promise, agree, plan, learn, need, offer, refuse, and after adjectives (happy to help).
  4. 4Use the to-infinitive to show purpose ('why?'): I went to the shop to buy milk.
  5. 5Use the bare infinitive (no 'to') after modal verbs and after make/let: She let him go; the teacher made us wait.

Practice

15 easy · 15 medium · 15 hard

10 random questions per test