After eating, we sat on the couch. Here, "after eating" is an example of: -

- সঠিক উত্তর: Participle 

- কিছু  prepositions আছে , যেগুলো  participle verb এর পূর্বে বসে এবং কোন ঘটনাকে  further emphasize অথবা events’ order, time, cause and effect  ইত্যাদিকে আরো clarify  করে। 

যেমন: এই শব্দগুলো:  like after, before, since, while and with.  for example:
After eating, we sat on the couch.
Since coming to England, I have met a lot of new people.

Participle:
- It is the form of a verb that usually ends in "ed" or "ing" and is used as an adjective:
- Participle একই সাথে Verb ও Adjective এর কাজ করে। 

Participle মূলত: তিন প্রকার: 
1. Present Participle. Ex: Do not disturb a sleeping dog. 
2. Past Participle. Ex: This is a book written by Charles Dickens. 
3. Perfect Participle. Ex: Having eaten rice, he went to bed. 

Source: A passage to the English Language by S.M Zakir Hussain & Essential Grammar in use by Raymond Murphy.