What form always follows a preposition?

Always the -ing form, as in "interested in learning French" — never "interested in to learn." This rule has no exceptions.

Why does "I look forward to hearing from you" use -ing and not "to hear"?

Because that "to" is functioning as a preposition, not part of an infinitive, so it triggers the -ing rule. Getting this right signals fluency in a closing line of a Writing Task 1 email.

Grammar

Gerunds & Infinitives (verb + verb)

When a verb is followed by another verb, do you use -ing or to? Learn the patterns behind "enjoy doing" vs. "want to do".

6 min read · Updated June 18, 2026 · By the Celpip.me editorial team · Free

Quick answer

Updated Sep 16, 2026

Use -ing after the 10 common gerund verbs like enjoy, avoid, finish, suggest, and consider, and use "to + base" after infinitive verbs like want, need, decide, hope, and plan; there's no logical rule for which group a verb falls into, so these lists must be memorized separately. One rule is always reliable: any verb right after a preposition takes -ing, as in "interested in learning."

What form always follows a preposition?: Always the -ing form, as in "interested in learning French" — never "interested in to learn." This rule has no exceptions.
Which verbs are followed by the infinitive (to + base)?: Common infinitive verbs include want, need, decide, hope, plan, promise, agree, offer, would like, expect, and learn, as in "They decided to move."
Why does "I look forward to hearing from you" use -ing and not "to hear"?: Because that "to" is functioning as a preposition, not part of an infinitive, so it triggers the -ing rule. Getting this right signals fluency in a closing line of a Writing Task 1 email.

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Key strategies

1.A gerund is the -ing form used as a noun: "Swimming is fun." Use it after prepositions: "good at cooking".
2.Some verbs take a gerund: enjoy, avoid, finish, suggest, consider, mind, practise.
3.Some verbs take an infinitive: want, need, decide, hope, plan, promise, agree, would like.
4.After a preposition, ALWAYS use the -ing form: "interested in learning", never "interested in to learn".

Two ways to follow a verb with a verb

Gerund (-ing): "I enjoy reading."
Infinitive (to + base): "I want to read."

Which one you use depends on the first verb. There is logic, but much of it is learned by exposure.

Common gerund verbs

enjoy, avoid, finish, suggest, consider, mind, practise, keep, miss, recommend.

"She suggested taking a break." "I avoid driving at night."

Common infinitive verbs

want, need, decide, hope, plan, promise, agree, offer, would like, expect, learn.

"They decided to move." "I would like to apply."

After a preposition → always -ing

This rule is reliable: any verb directly after a preposition takes the -ing form.

✓ "I am interested in learning French." ✗ "I am interested in to learn French." ✓ "Thank you for helping." "She is good at painting."

CELPIP application

These patterns appear constantly in natural speech and writing. Getting "I look forward to hearing from you" right (note: to here is a preposition, so -ing) signals fluency in a closing line of a Writing Task 1 email.

Check yourself

A quick self-check on this lesson — pick an answer, then see the explanation. Not graded.

1. Choose the correct form: "I enjoy ___ to music."

2. "We decided ___ a new apartment."

3. After a preposition: "She is interested in ___ a business."

4. Closing an email: "I look forward to ___ from you."

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