Is the sentence Mother had talked to teacher correct?

The sentence "Mother had talked to teacher" is grammatically correct, but it's a bit awkward and could be improved.

Here's why:

* Lack of specificity: We don't know *which* teacher Mother talked to.

* Informal tone: "Teacher" feels a bit too informal, especially if it's a formal situation.

Here are some better ways to say it:

* More specific: "Mother had talked to Mrs. Smith, the teacher."

* Formal tone: "Mother had spoken with the teacher."

* More context: "Mother had talked to the teacher about John's progress in math."

Ultimately, the best way to say it depends on the context of your writing.