Original sentence: In many languages, relative clauses are introduced by a special class of pronouns called relative pronouns; in the previous example, who is a relative pronoun.In other languages, relative clauses may be introduced by a special class of conjunctions called relativizers, or may be indicated by word order alone.In some languages, more than one of these may be possibilities
Edited sentence: In many languages, relative clauses are introduced by a special class of pronouns called relative pronouns.In the previous example, who is a relative pronoun