«زيد طبيب وماهر»
Zayd is a physician and is also skilled.
The textbook contrasts a pair of separate predicates with a combination that attaches the skill specifically to medicine. Being a physician and being skilled do not alone establish being a skilled physician; the skill might concern another field.
Thus, from “Zayd is a physician and is skilled,” one may not infer “Zayd is a skilled physician” without additional information. Two separate truths do not automatically justify a more specific combined predicate.