The term sentence structure refers to the conventions governing the construction of sentences. These rules may vary across languages and regions; this page is specifically concerned with the rules governing sentence construction or structure in standard English.
What Is a Sentence?
A sentence is a subject and a predicate working together to convey meaning. That is to say, every sentence contains something (a person, place, thing, or idea) and that thing must act in some way (even if the action is merely existing).
Subjects and Predicates
Subject: noun that takes action in a clause or sentence.
Predicate: action that occurs in a clause or sentence.
Predicates are the same thing as verbs, but “predicate” is the preferred terminology when discussing sentence structure.
Understanding Subjects and Predicates
Being able to identify subjects and predicates is requisite to understanding sentence structure. Understanding sentence structure will enable you to use punctuation with confidence and to better understand how the English language works. Let’s look at an example:
When attempting to examine the structure of a sentence, you should first ask yourself, what is the action? In the above example, “ran” is the action and, thus, the predicate. We can identify the subject by asking ourselves who or what takes the predicate? Or, in this case, who ran? Since “Jimmy” takes the predicate, “Jimmy” is the subject.
A predicate may also be a verb of being such as in this example:
The subject of the sentence is “Jimmy,” but what is the predicate? It is not “mad,” but rather “is.” This is because one cannot mad, but one can be, and “is” is a form of being. Mad describes the way Jimmy exists.
In addition to subjects and predicates, sentences may also contain objects. An object is any noun in a sentence or clause that does not take a predicate.
Let’s look at an example:
What is the predicate? Threw.
Once you have identified the predicate, you can locate the subject by asking yourself:
Who threw? Jimmy threw.
Because Jimmy takes the predicate, he is the subject of the sentence.
But what about Eric? Well, Eric doesn’t do anything in the sentence. “Eric” is merely acted upon by Jimmy; therefore, “Eric” is an object.
At this point my students often respond by saying, “But Eric does something. Eric gets hit by a pencil!” However, in the sentence, “Jimmy threw a pencil at Eric,” Eric does nothing. Contrarily, in the sentence, “Eric gets hit by a pencil,” Eric takes the predicate, “gets.” Because he takes the predicate, Eric is the subject. So, to reiterate, subjects are nouns in a sentence or clause that take predicates, and objects are nouns that do not.
An imperative sentence is a the one type of sentence that does not require a subject to be grammatically complete. Imperative sentences are used for commands and instructions. The subject of an imperative sentence is always “you,” and it is always implied.
For example, what is the subject in this sentence?
Example of an Imperative Sentence:
The first step in analyzing the structure of a sentence is to locate the predicate. “Stop” is the predicate in the above example, but who should stop? Most speakers would understand that the subject of the sentence is implicitly “you”; therefore, “you” should stop and the sentence is understood as such:
How an Imperative Sentence Is Understood:
Compound Subjects and Predicates
A sentence or clause must have at least one subject and predicate but may have more. When two or more subjects act on the same predicate, that sentence has a compound subject. When a subject has two or more predicates, we say that the sentence has a compound predicate.
Example of a Compound Subject:
What is the predicate? Went. Who went? Chris and I . Since two subjects act on the same predicate, this sentence has a compound subject.
Example of a Compound Predicate:
What is the predicate? Went and took. Who went and took? I. Since the subject “I” takes two predicates, going and taking, the sentence has a compound predicate.
Example of a Compound Subject and Compound Predicate:
It is possible for a sentence to have a compound subject and a compound predicate. What are the predicates in the above sentence? Went and took. Who “went” and took”? Shelly and I. Since the sentence has two subjects acting on the same two predicates, the sentence has a compound subject and compound predicate.
What Is a Clause?
A clause is a subject or group of subjects and a predicate or group of predicates working together. A sentence can have as few as one clause, or it may have many clauses. Clauses are to sentences what rooms are to houses. A sentence may have only one clause like a studio may have only one room, or a sentence may have many clauses like a house may have many rooms. Clauses are the building blocks of longer sentence.
An independent clause is a subject and a predicate working together and expressing a complete thought. An independent clause does not contain any subordinating or coordinating conjunctions, and could be removed from a larger sentence to stand on its own as a complete grammatical unit.
As with every clause, a dependent clause has a subject and a predicate, but unlike an independent clause, a dependent clause does not express a complete thought by itself. Dependent clauses contain either a subordinating or coordinating conjunction and must be joined to an independent clause. A dependent clause that is not joined with an independent clause is one type of sentence fragment.
A Dependent Clause Joined with an Independent Clause
This above sentence contains two clauses. The first clause is independent and could stand by itself as a complete grammatical unit:
The predicate phrase is “should leave,” and the subject is “we.” Because this clause does not contain any conjunctions, it expresses a complete thought and, therefore, is independent.
Contrarily, the second clause in the example sentence is dependent, meaning it does not express a complete thought by itself. Let’s take a close look:
Though the clause contains a subject and a predicate (getting and is), the clause also contains a subordinating conjunction (while). Because of the subordinating conjunction “while,” the clause is dependent on another clause to express a complete thought. If we remove the subordinating conjunction:
The clause is now independent, expresses a complete thought, and may form an independent grammatical unit.
Subordinating and coordinating conjunctions join clauses to make different sentence types.
Simple sentences have only one clause. Here is an example of a simple sentence:
Simple Sentence Example
What is the predicate? Took and went. Who took and went? Tom. So we have one subject taking two predicates, or a single subject and a group of predicates working together. Though this sentence has a compound predicate, it is still a single clause and thus a simple sentence.
Compound sentences have two or more clauses joined by a coordinating conjunction. The coordinating conjunctions are for, and, nor, but, or, yet, so. I use the acronym (F.A.N.B.O.Y.S.) to remember these. A new clause begins when the coordinator introduces the next subject. Here is an example:
Example of a Compound Sentence
The first clause has the subject, “Janie,” crying. The coordinating conjunction “but” allows me to connect my second clause (which has the subject “she” not getting her way) without creating a run-on sentence. Because this sentence has two subjects and predicates independent from one another, this sentence has two clauses. Because the two clause are joined with “but,” a coordinating conjunction, this is a compound sentence.
A complex sentence is two or more clauses joined with a subordinating conjunction. Here are some common subordinating conjunctions: unless, before, after, during, because, since, although, and if. Subordinating conjunctions will turn independent clauses into dependent clauses. These dependent clauses can be joined with independent clauses to make longer, more complex sentences.
Example of a Complex Sentence:
In this sentence we have two clauses joined with a subordinating conjunction; therefore, this is a complex sentence. Let’s take a closer look at the first clause:
Example of a Dependent Clause:
The predicate in the clause is actually a verb phrase: “can be.” Once we have identified the predicate, we locate the subject by asking ourselves, what can be? In this example it is “structure” or “sentence structure.” Because it has a subject and a predicate, the above example is a clause, but because of the subordinator, “Although,” the clause is dependent and requires an independent clause to express a complete idea. If we were to remove the subordinating conjunction, the clause would be independent:
The Same Clause, Now Independent
Do you see the difference? This is the power of conjunctions: they make clauses dependent thereby allowing us to build longer sentences without creating run-ons.
A run-on sentence is when two independent clauses are joined. It is a common misconception that run-on sentences have something to do with the length of sentence when this is not the case. Whether a sentence is considered a run-on actually has to do with the the structure of the sentence and not its length.
A Short Run-On Sentence
There are two clauses in the above example. The predicate of the first clause is “went” and the subject is “I.” In the second clause the predicate is “was” and the subject is “Mom.” Because no conjunction is used to coordinate or subordinate the two independent clauses, the above sentence is a run-on.
There is, however, one piece of punctuation with which we can join independent clauses, and that punctuation is the semicolon ( ; ). The semicolon’s primary use is to combine independent clauses. The semicolon should be used like a period or other end mark; however, the semicolon joins independent clauses whereas the other end marks separate them.
Example of Semicolon Usage
The semicolon is primarily used for elaborating ideas and carries an implicit “furthermore” with each use. When you are using or checking for proper use of the semicolon, you should substitute the word “furthermore” in its place. If the sentence still makes sense, and the semicolon is joining two independent clauses, then it is being used appropriately.
Sentence structure is a sprawling topic containing many rich nuances which I have not begun to cover. The goal of this page was to provide readers with a summary understanding of sentence structure in standard English. Please leave your comments or questions below, and thank you for visiting.