Does the following sentence form a gerund phrase The laughing boy sat down?

No, the sentence "The laughing boy sat down" does not contain a gerund phrase.

Here's why:

* Gerund: A gerund is a verb form ending in "-ing" that functions as a noun. Examples: *swimming*, *singing*, *reading*.

* Gerund phrase: A gerund phrase is a gerund plus any modifiers or objects that go with it. Examples: *swimming in the ocean*, *singing a beautiful song*, *reading a good book*.

In the sentence "The laughing boy sat down", the word "laughing" is a participle, not a gerund. It is modifying the noun "boy" to describe his state.

Let me know if you'd like to see an example of a sentence containing a gerund phrase!