However, moreover, then, nevertheless, therefore, accordingly, otherwise, thus, hence, besides, consequently, etc. They join two main clauses in a compound sentence by use of a semicolon and a comma. A grammatical unit that has a subject and a verb but cannot stand alone in a sentence because it does not express a complete thought. Subordinate clauses begin with subordinating conjunctions like what, that, who, which, since, when, before, after, if, because, or although that join ideas of unequal importance. They function as grammatical units in a sentence--- as nouns, adjectives, or adverbs. A subordinate clause used as a noun that is a subject, direct object, predicate nominative, object of a preposition, indirect object, or appositive; they are usually introduced by that, what, why, whether, who, which, or how. Most sentences containing noun clauses differ from those containing adj. and adv. clauses since with the noun clause removed they are no longer complete sentences.