V in n
III.4 The 'deal' group
These verbs are concerned with trading or work. The prepositional phrase indicates what goods or substances are involved. We include here work, in the sense of using a material to create something.
He deals in antiques and fine art.
Her shop specialises in decorative yet affordable silverware.
Some have never worked in clay before; others are among the world's leading potters.
In the case of specialize, the preposition in is sometimes followed by an '-ing' clause. The prepositional phrase indicates what activity someone's work involves.
deal specialize speculate trade traffic work
He specializes in treating people with epilepsy and schizophrenia.