a pre-existing medical condition的用法和样例：
- Many are held in poor conditions which have led to serious deterioration in their health or the exacerbation of existing medical conditions.
- Cook the pie for 20 minutes in a pre heated oven.
- There is even a medical condition called alcoholic dementia.
- He has a medical condition which precludes transfer.
- And if a doctor wants to discuss a medical condition,he speaks only to us.