The idea of the sentence is seemingly simple: A group of words containing a subject and verb which conveys a complete thought. First letter is capitalized. It ends with punctuation, such as a period.
But some sentences can get confusing. After all, not all sentences are created equal. Some are short and simple. Others are long and complex. Some turn out to not even be a sentence at all.
To help gain a better understanding of what a sentence is and, more importantly, what it is not, this page will cover what makes up a sentence, the functions a sentence can perform, and the structure of a sentence.
Sentence Function
To begin, specific sentences can be categorized in different ways. For example, a sentence may serve a specific function.
Four sentence functions
Declarative: Makes a statement.
- I will be going to class.
Imperative: Gives a command, makes a request, or gives instruction.
- Let’s go now.
Interrogative: Asks a question.
- Will you be taking your laptop?
Exclamatory: Expresses emotion.
- Look at this mess!
An individual sentence will only be able to be categorized as serving one of these four functions.
The function of a sentence is different from the structure of a sentence. Therefore, an individual sentence will typically fit into one of the four main sentence patterns, as well. (See Sentence Patterns)
Sentence Structure
Subject and Verb
Subject: The person, place, thing, or idea of the sentence.
- The student studied.
- Tom joined the group.
- I am hungry.
- Grab the phone. (The understood “You” is the subject of this imperative sentence.)
- Tom and Jane will be leaving soon.
Verb: The action of the sentence. What the subject is doing. (May also be referred to as the predicate.)
- The student studied.
- Tom joined the group.
- I am hungry.
- Grab the phone.
- Tom and Jane will be leaving soon.
Subject-Verb Agreement
Just as subjects can be either singular or plural (e.g. cat and cats; child and children; he and they), verbs can also be singular or plural.
Some examples of singular and plural verbs:
- lends (singular); lend (plural)
- goes (singular); go (plural)
- is (singular); are (plural)
To check, try using in a simple sentence:
- He lends money. (Singular); They lend money. (Plural)
- It goes there. (Singular); Those go there. (Plural)
- The child is angry. (Singular); The children are angry. (Plural)
There are many situations in which this becomes difficult to determine. Some of the more common errors include:
- When the subject is grammatically singular, but it describes more than one:
- The group
- Our family
- The Solar System
These are all singular subjects and require a singular verb:
- The group is happy.
- Our family goes to the park.
- The Solar System spans unimaginable area.
- When the subject comes before a phrase that starts with the word “of”:
- The group of adults
- Our family of chickens
- The Solar System of planets and stars
Ignore the phrase that begins with “of” and focus on the main subject.
- The group of adults is happy.
- Our family of chickens goes to the park.
- The Solar System of planets and stars spans unimaginable area.
- When two singular subjects are joined by the word “and,” consider them a compound subject (plural) and use a plural verb:
- He and she are going to the party. (Consider it the same as “They are going to the party.”)
- The cats and dogs are fighting again.
- My friends and I are at the park.
Phrase and Clauses
Clause: A group of words that does contain a subject and verb. A clause can be either Independent or Dependent:
- Independent Clause: Is also a complete thought, thus is able to stand alone.
- I liked the textbook that you loaned me. (Contains a subject, verb, and is a complete thought.)
- Dependent, or Subordinate, Clause: Is not a complete thought and depends upon an independent clause to express a complete thought. Types of Dependent Clauses are below:
– Adjective/Relative Clause – An adjective clause acts as an adjective, and it describes a noun in the sentence.
- I liked the textbook that you loaned me. (“that you loaned me” describes which textbook.)
– Adverb Clause – An adverb clause acts as an adverb, and it addresses where, when, how, and why something occurs.
- When I am ready, I will study. (“When I am ready” addresses when the studying will occur.)
– Noun Clause – A noun clause acts as a noun in a sentence. It can function as a subject, object, or complement.
- The leaking ball-point pen ruined my shirt. (“The leaking ball-point pen” is the subject of the verb “ruined.”)
Phrase: A group of words that does not contain a subject and verb. The major types of phrases are described below:
Absolute Phrase – An absolute phrase is a parenthetical element that modifies the entire sentence by adding information. It includes a subject, but no verb.
- The clock ticking, Matt rushed through the rest of his exam.
Appositive Phrase – An appositive phrase redefines, renames, or provides further information on the word directly before it.
- My favorite show, a multiple award winner, is on tonight.
- Our afternoon class, English 101, has been canceled today.
Gerund Phrase – A gerund phrase has a verb ending in “-ing” but acts as a noun.
- Studying often is a good way to improve test scores.
- Dancing the night away helped Judy relax.
Infinitive Phrase – An infinitive phrase includes the word “to” followed by a verb.
- The best way to understand the textbook is to read it.
- To get to the bottom of the hill is Jim’s goal on his ski trip.
Noun Phrase – A noun phrase contains a noun, as well as any modifiers. Noun phrases can be continuous or broken apart.
- The time to stop and face the music had come.
- The time had come to stop and face the music.
Participial Phrase – A participial phrase contains a verb ending in –ing, -ed, -en, -d, -t, -n, or –ne. It also modifies a noun.
- The professor, knowing his audience, proceeded carefully.
- Encouraged by applause, the performers returned to the stage.
Prepositional Phrase – A prepositional phrase contains a preposition and a noun/pronoun that is the object of the preposition. It often addresses the question of “Where?” or “When?”
- The book on the counter is mine.
- During the seventh inning stretch we will get some food.
Note: If you properly remove the prepositional phrase, a full sentence should still remain.
Sentence Patterns
Sentences can also be constructed in variety of different way, depending on how its dependent and independent clauses are used and organized.
Four main sentence constructions
Simple: Contains one independent clause.
- I study for class each night.
Compound: Contains at least two independent clauses joined by a coordinating conjunction. These coordinating conjunctions are: for, and, nor, but, or, yet, so
- I don’t complain, but he hates the library.
Complex: Contains one independent clause and one dependent clause. These sentences will include a subordinate conjunction. Examples of subordinate conjunctions are: after, although, because, if, since, when, where
- Because he worked so hard, John earned a high score. (“Because he worked so hard” is a dependent clause, and “John earned a high score” is an independent clause.)
Compound-Complex: Contains more than one independent clause and at least one dependent clause.
- While the library is not my favorite place, I don’t complain, but he hates going there. (“While the library is not my favorite place,” is a dependent clause. “I don’t complain, but he hates going there” is a compound sentence containing two independent clauses.)
Functions and Patterns together
An individual sentence will typically only be able to be categorized as one of the four pattern types.
However, an individual sentence will typically fit into one of the four main sentence types, as well. (See Sentence Function)
For example:
- I study for class each night. (A simple, declarative sentence.)
- Will you be going to class? (A simple, interrogative sentence.)
- Don’t complain, but we are heading to the library. (A compound, imperative sentence.)
- Because you worked so hard, I’m happy to tell you that you aced the exam! (A complex, exclamatory sentence.)
Sentence Errors
Fragment: A group of words that does not meet the criteria of a complete sentence, which are it 1.) has a subject, 2.) has a verb, and 3.) is a complete idea.
- Although she missed class. (Contains a subject and verb, but is not a complete idea. What about her missing class?)
- Some of the students who met these criteria. (Again, there is a subject and verb, but no complete idea. “Some of the students who met these criteria earned an A” would be one way to fix this fragment.)
- In a minute. (Does not contain a subject, verb, or a complete idea. People commonly speak using fragments, but this is not acceptable academic writing.)
Run-on (fused sentence): Two or more independent clauses improperly joined together. A run-on sentence is NOT affected by sentence length, meaning there can be considerably short run-ons, just as there can be extremely long, but grammatically correct sentences.
- I do not understand the assignment please provide further information.
This example contains two independent clauses:
- I do not understand the assignment.
- Please provide further information.
There are three ways to correct a run-on sentence:
- Create two separate sentences:
- I do not understand the assignment. Please provide further information.
- Use a semicolon (only if the independent clauses are logically connected):
- I do not understand the assignment; please provide further information.
- Separate by a comma and conjunction (for, and, nor, but, or, yet, so):
- I do not understand the assignment, so please provide further information.
Comma splice: A type of run-on sentence. Two or more independent clauses incorrectly separated by a comma.
- I do not understand the assignment, please provide further information.
As presented in the “Run on (fused sentence)” section, a comma splice can be fixed by creating two complete sentences, using a semicolon, or using a comma and conjunction.
Passive Voice: When the main noun (subject) of the sentence is positioned so that action is being acted upon it (changing it to the direct object of the sentence). While a sentence in passive voice is not grammatically incorrect, passive voice is considered inappropriate in formal writing, and active voice is preferred.
- The ball was kicked by George. (Passive voice)
- George kicked the ball. (Active voice)
In both sentences, the main idea is that George is the person who kicked the ball. However, in the passive voice example, “George” is not the grammatical main subject. Instead, “the ball” is the subject. Since “George” is part of a prepositional phrase (“by George”), it cannot be the main subject. Instead, it has become the direct object.
In the active voice example, this problem has been resolved. “George” is the rightful main subject. “kicked” is the the action “George” performs. The direct object (or the answer to question “What was kicked?”) is “the ball.”