a medical practitioner的用法和样例：
- To be used only as directed by a medical practitioner.
- She was a medical practitioner before she entered politics.
- Letter on official letterhead from a medical practitioner or medical professioal supporting the circumstances.
- His father is a medical practitioner, and later settled in a camp near the city of Scandinavia, a village.
- Directions: Take one (1) caplet daily with any meal for maximum daily results, or as directed by a medical practitioner.