Overview

A clause is a group of words that has a subject and a predicate and is used as part of a sentence. A main, or independent, clause can stand alone as a sentence. Consider the following: "The candidate spoke, and the voters listened." The candidate spoke and the voters listened are both main clauses. They could be divided into two complete thoughts or sentences.

A subordinate, or dependent, clause, although it also has a subject and predicate, cannot stand alone as a sentence. For example, "When the candidate spoke, the voters listened." The subordinate clause, When the candidate spoke, is not a complete thought or sentence; it must be attached to the main clause the voters listened. Subordinate clauses can act as adjectives, adverbs, or nouns. In the previous example, when the candidate spoke functions like an adverb.

Sentence structure can be simple, consisting solely of a main clause. The following is a simple sentence: "The candidate spoke." Compound sentences consist of two main clauses. "The candidate spoke, and the voters listened" is a compound sentence. Complex sentences consist of a main clause and one or more subordinate clauses. For instance, "When the candidate spoke, the voters listened." Finally, compound-complex sentences have more than one main clause and at least one subordinate clause. "People must choose a candidate, but they should make their decisions after they listen to the candidates speak."

Sentences have four different functions. Declarative sentences make statements and end with a period. For example, "The candidate spoke." Imperative sentences make requests or commands and also end with a period. "Speak to the citizens" is an imperative sentence. Interrogative sentences ask questions and end with a question mark. For instance, "Did the candidate already speak to the voters?" Finally, exclamatory sentences express strong emotions and end with an exclamation point. "The candidate gave a great speech!"

Sentence fragments and run-on sentences are common errors produced when working with clauses and sentences. A sentence fragment is punctuated as if it were a sentence although it is missing a subject or a verb, or it is a subordinate main clause standing alone. Correct these errors by joining the fragment to an idea that comes before or after it, or add additional words to form a complete sentence. A comma splice probably is the most common type of run-on sentence; it occurs when two main clauses are separated by a comma rather than a period or semicolon. Correct comma splices by replacing the comma with a period or other end mark, and start the new sentence with a capital letter. Alternatively, change the comma to a semicolon or insert a coordinating conjunction after the comma.