A complex sentence consists of an independent clause (simple sentence) and one or more
dependent clauses (subordinating clauses). The dependent clause is introduced by either a
subordinate conjunction (for an adverbial clause) or a relative pronoun (for an adjectival
clause).
1. Some common subordinating conjunctions (adverbial clauses): after, (al)though, as, because,
before, if, once, since, unless, until, when, while
2. Relative pronouns (adjectival clauses): who/that, whom, whose (people); that, which
(animals, things).