What is the to-infinitive?
The to-infinitive is to + the plain verb: to play, to eat, to learn. It does not change for he, she or they.
Three jobs of the to-infinitive
| Job | Example | Meaning |
|---|---|---|
| Noun | To learn is fun. / I want to learn. | names an action |
| Adjective | a book to read, time to go | describes a noun |
| Adverb | I went out to play. | shows purpose (in order to) |
What is a gerund?
A gerund is a verb + ing that works as a noun: swimming, reading, cooking. It names the action as a thing.
A gerund can be the subject: Reading helps me relax. It can be the object: I enjoy reading. It can also follow a preposition: I am good at drawing. Thank you for helping.
Do not mix it up with the -ing verb in the progressive (I am reading), where -ing is part of the verb.
Verbs that take to, -ing or both
| Pattern | Common verbs | Example |
|---|---|---|
| verb + to | want, hope, decide, plan, learn, need, promise | She decided to stay. |
| verb + -ing | enjoy, finish, mind, avoid, practise, keep, suggest | He finished reading. |
| both (same meaning) | like, love, hate, start, begin | It started to rain / raining. |
A few verbs change meaning: stop to rest (stop in order to rest) vs stop resting (finish the rest). Learn the verb with its pattern.
Key formulas and definitions
- to-infinitive: to + plain verb (to play)
- gerund: verb + ing used as a noun (swimming)
- want / hope / decide / plan + to + verb
- enjoy / finish / mind / avoid + verb-ing
- preposition + verb-ing (good at drawing)
Worked examples
1. Fill in with to + verb or -ing: She decided ____ (stay) at home.
to stay. decide takes the to-infinitive.
2. Fill in: I enjoy ____ (swim) in the evening.
swimming. enjoy takes a gerund.
3. Name the job of the underlined words: I went to the market <u>to buy vegetables</u>.
Adverb of purpose. It tells why I went (in order to buy vegetables).
4. Is "Reading" the subject here: "Reading before bed helps me sleep"?
Yes. Reading is a gerund used as the subject of the sentence.
5. Correct: He finished to write his essay.
He finished writing his essay. finish takes a gerund, not to.
Common mistakes
- Saying "I enjoy to swim". After enjoy use -ing: I enjoy swimming.
- Saying "I want going home". After want use to: I want to go home.
- Adding -s or -ed to the plain verb after to: "to goes", "to went". Keep it plain: to go.
- Confusing a gerund with the progressive: in "I am swimming" swimming is part of the verb, not a noun.