Question

1. He went to a teacher training center to learn Python.

2. He went to a teachers training center to learn Python.

3. He went to a teacher's training center to learn Python.

4. He went to a teachers' training center to learn Python.
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Which ones are grammatical?

Answer 1

I wouldn't use any of those with possessives. Here's what I'd use:

He went to a teacher-training center to learn Python.