What Is a Sentence?

What is a sentence?

Before we can answer that question, we need to know what a sentence is not.

A sentence is not a phrase.

A phrase is a group of words that has neither a subject nor a verb. Therefore, it cannot express a complete thought. (The subject is the word, or, sometimes, group of words about which the rest of the sentence, its predicate, makes a point.) Many phrases work as adverbs or adjectives. These are phrases: “under the table,” “in the blue suit.”

A sentence is also not a dependent clause. (A dependent clause is a group of words that has both a subject and a verb but does not express a complete thought.) Many dependent clauses also work as adverbs or adjectives. These are also dependent clauses: “which was fun” (“which” is the subject; “was fun” is the verb), “that explains everything” (“that” is the subject; “explains” is the verb).

Let's review what we have learned:

• A phrase = a group of words with neither a subject nor a verb
• A dependent clause = a group of words with both a subject and a verb.
• Neither a phrase nor a dependent clause expresses a complete thought.
• Many phrases and dependent clauses act as adverbs or adjectives.

Now, we can answer our original question: what is a sentence?

A sentence is an independent clause. (An independent clause has both a subject and a verb and expresses a complete thought.) An independent clause is also known as a simple sentence. How do dependent and independent clauses differ? Let's review:

• A dependent clause has neither a subject nor a verb.
• An independent clause has both a subject and a verb.
• A dependent clause does not express a complete thought.
• An independent clause does express a complete thought.

In English, the natural word order, or syntax, is subject-verb-object. (A direct object is a word that receives the action expressed by a verb.)

Some verbs express action; they are known as action verbs. Other verbs express a state of existence, or being; they are known as verbs of being. A third group of verbs link the subject of the sentence to another word in the rest of the sentence (the predicate). The verbs in this third group of verbs are called linking verbs. Here is an example of each:

• John ate cake. (action verb)
• John is old. (verb of being)
• John became an athlete. (linking verb)

An action verb may or may not have a direct object. If an action verb does have a direct object, the action verb is said to be transitive; in other words, transitive verbs have objects. If an action verb does not have a direct object, the action verb is said to be intransitive. (The prefix “-in” means “not”: therefore, an independent clause is not a dependent clause, and an intransitive verb is not a transitive verb.) Remember: if an action verb has a direct object, it is transitive; if it does not, it is intransitive. Here is an example of a transitive and an intransitive verb:

• John ate cake. (transitive verb)
• John ate quickly. (intransitive verb).

To test whether a verb is transitive or intransitive, ask the question “what?” immediately after the verb. If there is an answer to this question, the verb is transitive, and the word that answers the question is the object of the transitive verb. NOTE: You must ask “what?,” not “how?”

• John ate WHAT? cake. (transitive verb; “cake” = direct object)
• John ate WHAT? quickly. (intransitive verb; “quickly tells HOW, not WHAT).

Remember, the natural word order, or syntax, of the English language is subject-verb-object (if there is an object).

Sentences can be grouped in two ways. Sentences can be according to how they are constructed, or built, and sentences can be grouped according to how they function, or what they do.

When grouped by how they are constructed, or built, there are four types of sentences:

1. Simple = one independent clause: “John ate cake.”
2. Compound = two independent clauses, joined by a comma and a conjunction or by a semicolon: “John ate cake, but Nancy ate pie” (or “John ate cake; Nancy ate pie”).
3. Complex = one (or more) dependent clause(s) and one independent clause: “We went dancing, which was fun”: “We went dancing” is an independent clause; “which was fun” is a dependent clause.
4. Compound-complex = one (or more) dependent clause(s) and two independent clause: “We had dinner, and we went dancing, which was fun”: “We went dancing” is an independent clause; “which was fun” is a dependent clause.

When grouped by their function, or what they do, there are also four types of sentences:

1. Declarative = a sentence that states a fact or expresses an opinion (claim): both “George Washington was the first U. S. president” (a statement of fact) and “George Washington was an effective president” (an expression of an opinion) are declarative sentences. (A declarative sentence ends with a period.)
2. Interrogative = a sentence that asks a question: “Who was the first U. S. president?” is an interrogative sentence. (An interrogative sentence ends with a question mark.)
3. Imperative = a sentence that makes a request or issues an order: “Pass the salt” and “All hands on deck!” are both imperative sentences. (An imperative sentence may end with a period or an exclamation point.)
4. Exclamatory = a sentence that expresses strong emotion: “He hit her!” (An exclamatory sentence ends with an exclamation point.)

As we mentioned before, many phrases and dependent clauses are used as adjectives or adverbs. Here are a couple examples:

• The cat ran under the table (the phrase “under the table” is used as an adverb, telling where the cat “ran”).
• The man in the blue suit is my uncle (the phrase “in the blue suit” is used as an adjective, explaining which “man” is the uncle.)
• We went dancing, which was fun (the dependent clause, “which was fun,” is used as an adverb, telling what action--”went dancing”—was fun.)
• The book that I read was exciting (the dependent clause, “that I read,” describes the “book.”)

We mentioned two words that are sometimes thought to be the same (and can be), but are not necessarily the same: “verb” and “predicate.” Remember, a verb is a word, or a group of words, that names an action, expresses a state of being, or links the subject of the sentence with another word or group of words in the sentence. A predicate consists of all the words to the right of the subject of the sentence, including the verb and any other words. In each of these sentences, the predicate is highlighted in bold:

• John ate.
• John ate cake.
• John ate quickly.
• John ate the cake quickly.
• John ate the chocolate cake quickly.
• John ate the chocolate cake quickly, before Brenda could have any.

A predicate can be a single word, when the predicate consists of only an intransitive verb, or a predicate can be several, or even many, words.

A longer sentence can be thought of as having three parts: a beginning, a middle, and an end (although not all longer sentences have all three of these parts):

“Seven people were injured” might be the main idea.

You might decide to explain when this incident happened:

During the recent tornado, seven people were injured. (Now, the sentence has two parts, a beginning and an end). The phrase “During the tornado” introduces the main idea that ends the sentence; therefore, it might be called an introductory phrase.

Maybe you decide to also clarify the point that “no one was killed” by adding what might be called an afterthought:

During the tornado, seven people were injured, but no one was killed.

Now, your sentence has three parts: an introduction, or beginning “During the tornado”), a middle, the main idea (“seven people were injured”), and an afterthought, at the end (“but no one was killed”).

Tips on Writing Sentences

1. Remember that, at a minimum, a sentence has a subject and a verb and expresses
   a complete thought.
2. Remember that the natural syntax of the English language is subject-verb-object.
3. Use active voice (that is, employ an active verb, a verb that expresses an action).
4. Start by expressing your main idea.
5. Add phrases and dependent clauses to add details to your main idea. Most will explain answer or apply to one of these questions: Who?, Whom?, What?, When?, Where?, How?, Why?, How many? How much?
6. Vary sentence length and type. Include both shorter, longer, and medium-length sentences. Include declarative, interrogative, imperative, and emphatic sentences (as appropriate).
7. Think about what you want to say and how to say it before, during, and after you write each sentence.
8. Read each sentence as you go, to be sure that it says what you want to say, how you want to say it. Also ask yourself whether you can say it better or want to add (or subtract) details.

Table Showing the Relationships between Types of Information to Relate and Related Parts of Speech

TYPE of INFORMATION (QUESTION)	PART OF SPEECH
WHO? and WHAT?; WHOM?	Subject, direct object
WHEN? and WHERE?	Adverb, adverbial phrase, adverbial clause
HOW?	Adverb, adverbial phrase, adverbial clause
WHY?	Infinitive phrase, dependent clause used as an introduction or an afterthought
HOW MANY? or HOW MUCH?	Adjective, adjectival phrase, adjectival clause

• The building burned. (SUBJECT = WHAT?)
• John runs. (SUBJECT = WHO?)

• They painted the building. (OBJECT = WHAT?)
• Bill hit John. (OBJECT = WHOM?)

• The building burned yesterday. (ADVERB = WHEN?)
• John runs daily. (ADVER = WHEN?)
• The building burned during the night. (ADVERBIAL PHRASE = WHEN?)
• John runs after breakfast. (ADVERBIAL PHRASE = WHEN?)
• The building burned after lightning struck it. (ADVERBIAL CLAUSE = WHEN?)
• John runs well now that he has been coached. (ADVERBIAL CLAUSE = WHEN?)

• The building burned quickly. (ADVERB = HOW?)
• John runs well. (ADVERB = HOW?)
• The building burned to the ground. (ADVERBIAL PHRASE = HOW?)
• John runs like the wind. (ADVERBIAL PHRASE = HOW?)
• The building burned when lightning struck its roof. (ADVERBIAL CLAUSE = HOW?)
• John runs after he does his stretching exercises. (ADVERBIAL CLAUSE = HOW?)

• To demolish the building, the crew set it afire. (INFINITIVE PHRASE = WHY?)
• Because the building is unsafe, the town council ordered it to be demolished (INTRODUCTORY DEPENDENT CLAUSE = WHY?)
• The town council ordered the building to be demolished, because it is unsafe. (DEPENDENT CLAUSE USED AS AN AFTERTHOUGHT = WHY?)

• There are six chairs at the dining room table. (ADJECTIVE = HOW MANY?)
  The aquarium holds fifty gallons of water. (ADJECTIVE + HOW MUCH?)
• Pick any of the four alternatives. (ADJECTIVAL PHRASE = HOW MANY?)
• We should finish the task in three hours. (ADJECTIVAL PHRASE = HOW MUCH?)
• After he chopped down the two trees, he planted four others. (ADJECTIVAL CLAUSE = HOW MANY?)
• A ton of water falls over the spillway during every half hour. (ADJECTIVAL CLAUSE = HOW MANY?)