What is the progressive form of your mother writes a letter to uncle nestor?

The progressive form of "Your mother writes a letter to Uncle Nestor" is "Your mother is writing a letter to Uncle Nestor."

Here's why:

* Progressive tenses (also called continuous tenses) use the verb "be" followed by the present participle (-ing form of the verb).

* This form emphasizes an ongoing action.

* In this case, the action of writing is happening at the moment of speaking.