Barry Budweiser thought aloud to himself, and he wondered if indeed he'd had too many beers. When Barry Budweiser thought aloud to himself, he wondered if he'd had too many beers since his girlfriend now appeared to have two heads. When and since in the silly sentence above are subordinating conjunctions. These words show that a dependent clause follows. The rumor that Islander fans are rowdy may have been started by a Ranger fan.
Adverbial clauses modify a verb or adjective.
The dependent clause can be part of an independent clause. A sentence fragment either lacks a subject or a complete verb, or does not express a complete thought. Swimming in the lake is forbidden . The professor gone to the office. The professor has gone to the office.