There is no way to judge without seeing them within their structured sentences. #1 is not a 'description of a teacher', however, and 'plenty of' in #3 is too casual.
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Anonymousinstead of using 'plenty of', can I use 'a lot of' to make it formal, or what phrase should I use?A good deal of sounds better to me. You could also be specific and tell how many months of experience, hours of practicum, etc.