Preposition + -ing

Prepositions (in, on, at, of, for, about, with, without, by, before, after, instead of…) are followed by nouns. If you want a verb straight after a preposition, it must take the -ing form (a gerund) — not the base form and not to + verb.

💡Many languages leave the verb unchanged after words like “before” or “by”. English does not: right after a preposition the verb must end in -ing. Whenever you see before, after, by, without, instead of, for, about… followed by a verb, check the -ing.

1. By + -ing — how you do something or how you get a result

• You can save a lot of money by cooking at home.

• She improved her English by watching films with English subtitles.

2. Without + -ing — something that you might expect did not happen

• He left the party without saying goodbye.

• Don't go out without locking the door.

3. Before / after + -ing — one action before or after another

• Wash your hands before eating.

• After finishing university, Minh moved to Da Nang.

• Before leaving, please turn off the lights.

  not: Before to leave

4. Instead of + -ing — doing one thing in place of another

• Instead of taking a taxi, we walked home.

• Why don't you call her instead of sending a message?

5. Thanks for / sorry for + -ing — thanking or apologising for something you did

• Thanks for helping me with the move.

• Sorry for not replying sooner — I was busy with exams.

  negative: not + -ing

6. How about / what about + -ing — making a suggestion

• How about having a picnic this weekend?

Many adjectives, verbs and nouns come with a fixed preposition (see the lessons “Adjective + preposition” and “Verb + preposition”). When an action follows, that verb also takes -ing.

• My dad is really good at cooking Vietnamese food.

• Phong is thinking about moving to Da Nang.

• Did they succeed in finding a flat?

  not: succeed to find

• I love the idea of living in the countryside.

You can put a person before the -ing to show who does the action: I'm tired of people telling me what to do. We're worried about him driving at night.

Usually to goes with the base form (want to go). But in some phrases to is a preposition, so it is followed by a noun or -ing: look forward to, be/get used to, object to, prefer … to …, when it comes to, in addition to.

• We're really looking forward to seeing you.

  not: to see

• I prefer walking to driving in the city.

• When it comes to cooking, my brother is the expert.

💡Test: put a noun after “to”. If the sentence still works (I'm looking forward to the holiday), “to” is a preposition → use -ing. If it doesn't (I want to the holiday — wrong), use the base form. See also the lesson “Be used to + -ing”.

• Negative: put not before the -ing — Sorry for not calling. / She got sick by not eating properly.
• Passive: being + past participle — He got into the building without being seen. / I hate the idea of being watched.
• For an earlier action you can use having + past participle, but plain -ing is usually clear enough: He was proud of winning / of having won the prize.
• The hidden subject of the -ing is the subject of the main clause: After finishing lunch, we went back to work (we finished lunch). Avoid After finishing lunch, the meeting started — it sounds as if the meeting had lunch.
• Before / after are also conjunctions, so a full clause works too: Before I left, I called my mum. = Before leaving, I called my mum. The -ing version is shorter when both parts have the same subject.

• ✗I'm interested in learn Korean.

  ✓I'm interested in learning Korean.

  After the preposition in, the verb takes -ing.

• ✗Before to leave, please turn off the lights.

  ✓Before leaving, please turn off the lights.

  Before is a preposition, not followed by to + verb.

• ✗Thanks for help me.

  ✓Thanks for helping me.

  For is a preposition → helping.

• ✗He's thinking about to buy a car.

  ✓He's thinking about buying a car.

  Preposition + -ing, not + to + verb.

• ✗She's good in drawing.

  ✓She's good at drawing.

  The preposition after good is at.

• ✗He left without say anything.

  ✓He left without saying anything.

  Without + -ing.