While doing my TOEFL prep I encountered the following statement where I am asked to find which of the bold words is being used wrongly in the sentence:
If one has a special medical condition such as diabetes, epilepsy, or allergy, it is advisable that they carry some kind of identification in order to avoid being given improper medication in an emergency.
The bold they and carry should be treated as two words (meaning, only one of them can be wrong, but not both).
I would say being is used wrongly just because when I reread the statement it doesn't sound right, even though most of the time a gerund is used after the erb avoid.