Complete Sentence Structure: How to Write Complete Sentences

A complete sentence is a group of words that conveys a complete idea. Complete sentences must have at least one subject and predicate, the necessary pieces of an independent clause. A subject is the first unit of information and contains a noun; the predicate expands upon that information and contains a verb or phrase. Complete sentences start with a capital letter, and they end with a period, exclamation point, or question mark.

Complete sentences, incomplete sentences, and run-on sentences all convey ideas with varying degrees of information.

• Complete sentence: Complete sentences express a complete thought or idea. A complete sentence must have one main clause and a predicate.
• Sentence fragments: Sentence fragments have some information but are incomplete on their own. For example, “Moved south” is an incomplete sentence because it lacks a clear subject. The person reading it would rightly ask “who” or “what” moved south. Fragments may often begin with prepositional phrases, such as “although” and “before.”
• Run-on sentence: Run-on sentences have too much information. Run-on sentences are typically long and have various subjects instead of one main subject. Run-on sentences also contain comma splices. The comma, rather than linking a subordinate clause to the main clause, links together two thoughts that would better be expressed as separate sentences (or as causes of differing importance in a complex sentence).

When writing a complete sentence, begin with a main subject. The subject tells who or what your sentence will be about. Next, follow the subject with a predicate, which offers information about the subject or what the subject is doing. Predicates, which typically begin with a verb, can also link the subject to another noun or verb via a linking verb.

Complete sentences can be long or short, complex or compound, interrogative, declarative, or exclamatory. In any form, complete sentences express a complete thought. Consider the following examples of the complete sentence structure:

1. 1. “The art thief had a weakness for eighteenth-century masterworks.” In this first sentence, the subject or the main noun is “The art thief.” The predicate is “had a weakness for,” which describes something about the subject.
2. 2. “My wife has a green thumb, but I can’t seem to keep any plants alive.” This sentence has two subjects, the author and their wife. Linking the two subjects together to express a single idea—the comparative abilities of these people with plants—makes it a compound sentence, with the clauses separated by a comma. In the first clause, “has” is the main verb relating to the wife, and in the second, “keep” is the main verb about the author.
3. 3. “Every time I hear violin music I cry, which is why I avoid the symphony.” In this sentence, there is an independent clause, “every time I hear violin music I cry,” and a subordinate or dependent clause, “which is why,” that further elaborates on the writer’s situation.

Sentences can express statements, questions, commands, or exclamations.

1. 1. Imperative sentence: An imperative sentence addresses an implied second person with a request, command, instruction, or invitation.
2. 2. Declarative sentence: A declarative sentence is a sentence that makes a statement, provides a fact, offers an explanation, or conveys information.
3. 3. Interrogative sentence: This type of sentence asks a question and ends with a question mark.
4. 4. Exclamatory sentence: This sentence expresses excitement or emotion, contains a subject, and ends with an exclamation point.

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