Like all dependent clauses, it contains a verb (and also a subject unless it is a non-finite dependent clause).

In Indo-European languages, a relative clause, also called an adjectival clause or an adjective clause, meets three requirements: In English, in some instances the subordinator that can be omitted. The dependent clause serves as the subject of the main clause.) The dependent clause serves as the object of the main-clause verb 'know'.) A clause is a content clause if a pronoun ( he, she, it, or they) could be substituted for it. Notice that some of these words also introduce relative and adverbial clauses.

Some of the English words that introduce content clauses are that, who (and formal whom), whoever (and formal whomever), whether, why, what, how, when, and where. It can be a subject, predicate nominative, direct object, appositive, indirect object, or object of the preposition.

A content clause, also known as a 'noun clause', provides content implied or commented upon by its main clause.

What is a relative adverb