If you’ve made it through the section on parts of speech (see the video above for a thorough review), then you’re ready to tackle sentence structure.

This section has three parts. First we’ll talk about the different components of a sentence. How do you find the subject of a sentence? What is a phrase or a clause? How can you combine these into complete sentences?

After that, we give some constructive advice about how to make your sentences more stylish and concise.

Finally, we’ll help you learn what sentence errors to avoid.

The Goal

Much of this material is challenging, so take your time and do the exercises. The reward is worth it though: some time spent learning about sentence structure will make you a much better writer.

Finding the subject


Figuring out what the subject of a sentence is can be surprisingly difficult. Take a complex sentence like the following:

Starting in 2011, the civil war in Syria led to sustained conflict between the forces of President Bashar al-Assad and various militia groups (including Isis).

How do you even begin to find the subject of the sentence? What if the sentence contains more than one clause? Why should you care about the subject of the sentence?

Let’s see if we can answer these questions and provide enough practice to let you find the subject with confidence.

(As for our difficult example, the subject is “the civil war,” and soon you will know exactly why).

Subject and Predicate

Every sentence consists of least a subject and a predicate. A complex sentence with multiple clauses may have more than one subject and predicate.

The subject is what the sentence is about; the predicate describes the subject:

Subject + Predicate
I love strawberries
Henry laughed his head off.
The Tornado has crossed the state border.

As an aside, it’s a curious fact that back in the Middle Ages some scholars argued that the subject and predicate are analogous to feminine and masculine gender roles.[i] The predicate was said to be masculine because it contains the verb (the action) and because it modifies and fixes the meaning of the feminine subject. So there you go–even grammar has its battle of the sexes!

Defining the subject

In the previous section we gave a simple definition of the subject: it’s what the sentence is about. In practice, that definition is too vague.

A more precise definition is as follows: the subject is the part of the sentence that is doing the action of the main verb. The subject is usually a noun or pronoun, but it can also be a longer phrase.

Let’s look at an example:

The students represented Kiribati at the Model United Nations Conference in New York.

Step 1: Find the main verb: represented.

Step 2: Ask the right question: who or what is doing the action of the verb?

Step 3: Apply this question to the sentence: who or what represented Kiribati?

Step 4: Answer the question: The students.

The subject of the sentence is therefore the students.

If you follow this procedure rigorously you will be much more successful. There are just a few tricky cases (described below) where you need to know some extra rules.

Simple and Complete Subject

We can make a useful distinction between the simple and the complete subject. The complete subject is the subject and all its modifiers. The simple subject is the core idea without all the description:

Hans Zimmer’s dramatic sound track to the movie Inception remains one of my favourite compositions.

Complete subject: Hans Zimmer’s dramatic sound track to the movie Inception.

Simple subject: sound track.

If you’re having trouble seeing the difference, it may help to break down the subject further:

Parts of the Subject Parts of Speech
Hans Zimmer’s Noun acting as adjective
dramatic Adjective
sound track Noun
to the movie Inception Prepositional phrase

Being able to spot the simple subject will help you take apart sentences more easily.

Multiple clauses

So far we’ve looked only at sentences that contain a single subject. Yet if the sentence has multiple clauses it will also have multiple subjects. That’s because every clause has its own subject (and verb).

Here’s an example of two independent clauses joined by a coordinating conjunction (and):

Reginald blew the whistle and the game was over.

In this case each independent clause could be its own sentence. But even dependent clauses contain a subject and a verb:

Though the woolly mammoth is extinct, it remains a beloved subject of cartoonists.

Dependent clause: Though the woolly mammoth is extinct.

Subjects: the woolly mammoth, it.

And if we want to get really fancy we can have numerous clauses (and subjects) in a single sentence:

When I was younger, my family doctor, who struggled with back pain herself, suggested that I make an appointment with a chiropractor.

Subjects: I (was), my family doctor (suggested), who (struggled), I (make).

For now we will ignore these more complex sentences, but when you’ve mastered subjects you can go on to study clauses in more detail.

Tricky subjects

If you want to be an expert at finding the subject then you may want to familiarize yourself with some instances where the subject is harder to spot.

Linking verbs

Linking verbs are not traditional action verbs, and so it’s easy to overlook them when you’re trying to find the main verb.

The most common linking verb is to be in all its many forms (is, are, were, etc.). A linking verb is followed by a noun or an adjective that describes the subject:

Martha is sick.

Jason was goalie.

Linking verbs also follow more complex subjects:

The day before Christmas is my birthday too!

The global shift to renewable energy is inevitable.

In both examples the linking verb is is and the subject is highlighted.


When you’re looking for the main verb of the sentence, watch out for verbals (especially present participles and infinitives). They may look like action words, but they will never be the main verb unless they’re part of a verb phrase.

In fact, verbals are often part of the subject of the sentence:

Signing your child up for every last sport may be detrimental to your own health.

To think kind thoughts shouldn’t be so hard.

For the sake of clarity we’ve highlighted the complete subjects. The main verbs are may be and shouldn’t be.


Be careful with sentences that start with there is or there are. These are called expletives and they don’t contain the subject of the sentence:

There are three burgers left.

There is a strange man at the door.

To find the subject you should ask “who or what is/are there?” The answers are three burgers and a strange man.


When a sentence is a command (and imperative), the subject is implied:

Show me the money!

Question: who or what will show me (the money)?

Answer: you.

The subject is therefore a person who may not be named in the sentence.

The passive voice

Don’t be fooled by the passive voice. Take the following sentence:

The accident was caused by the bus driver’s son.

If you ask “who or what was caused?” you will get the correct subject (the accident), even though in reality it was the son who caused the accident. In other words, if the verb is passive then the action happens to the subject.

Reverse order

In English, most sentences follow a particular order, with the subject coming before the main verb. Occasionally the order is reversed:

Among the ingredients is stardust.

In this case the subject is “stardust.”


[i] For more detail, see Alan of Lille’s De Planctu Naturae (The Plaint of Nature). For a scholarly treatment, check out Jan Ziolkowski’s Alan of Lille’s Grammar of Sex: The Meaning of Grammar to a Twelfth-Century Intellectual (1985).

Independent and Dependent Clauses


Clauses are large grammatical units composed of many parts of speech. At the core they generally contain a subject and a verb, as well as any number of modifiers.

Here are some examples of clauses:

When the weather improves a bit

I love pogo sticks

Have you met my friend James?

Although in principle I like the colour mauve

Each of these clauses consists of a number of parts of speech and phrases that together make up an idea. Some of the examples can be complete sentences by themselves and others cannot.

When a clause can stand by itself it is called an independent clause. When it has to be connected to another clause, it is a dependent or subordinate clause.

Independent clauses

An independent clause normally has a subject and a main verb and can function as a complete sentence. Here are a few examples:

I love online learning.

Subject: I.
Verb: love.

Tears trickled down his cheeks.

Subject: Tears.
Verb: trickled.

The cat ate the goldfish.

Subject: The cat.
Verb: ate.

While this may seem basic, the one thing that gives students trouble is when you use a coordinating conjunction to connect clauses:

Stalagmites grow up and stalactites hang down.

I couldn’t decide betwen Adobe Illustrator or Corel Draw, so I bought them both.

In these cases you should not consider the coordinating conjunction as part of either clause. It just sits in between the independent clauses.

As you’ll read below, the opposite is true of subordinating conjunctions.

Dependent clauses

A dependent clause cannot be a complete sentence by itself. That is because it starts with a word that connects to a main clause. Often the word is a subordinating conjunction or a relative pronoun:

Subordinating conjunction: when, while, although, because, since, etc.

Relative pronoun: who, which, whose, whom, what, that

Dependent clauses that start with a relative pronoun are called relative clauses.

A dependent clause, then, cannot be a sentence by itself:

While I shot the sheriff

Which everyone saw

Who talked to me

Note that the relative pronoun not only connects the dependent clause, but often also acts as its subject.

Now let’s see how we can add these dependent clauses to a sentence:

As my father used to say, the apple does not fall far from the tree.

The capybara, which is native to South America, is the largest rodent in the world.

Note that in the second example the dependent clause interrupts the main clause and provides more information about a noun phrase (“The capybara”).

We all combine clauses intuitively, but recognizing how it works will help you write balanced and complex sentences.

Implied Clauses

In addition to the regular clauses discussed so far, we sometimes come across sentence elements that function like clauses but are missing a clear subject or verb. It may be helpful to think of these as hidden or implied clauses (though neither is strictly a technical term). Typically these are dependent clauses, and they come in two kinds: non-finite and verbless.

Non-Finite Clauses

Regular clauses have a finite verb as the main verb. A finite verb can be conjugated for different subjects and can show tense. For example, notice how the verb changes in form when we write “I swim,” “he was swimming,” and “they swam.”

By contrast, non-finite verbs do not change form. In our Parts of Speech section, we used the word “verbals” for non-finite verbs, and although grammarians argue about terminology, all we need to know is that they are roughly the same.

Non-finite clauses, therefore, do not contain a regular verb but include an infinitive, present participle, or past participle. In each case, there is no other verb (as in “he was swimming”) that would make the verb phrase finite.

There are four types of non-finite clauses.

1. Infinitive.

The main thing is to look confident.

Mentally we can reconstruct the non-finite clause as “he looks confident.” Even though the subject is missing and we have an infinitive (“to look”), we can recognize the similarity to a clause.

2. Bare Infinitive.

A slight variation is the bare infinitive, where the word “to” is left out:

He bade me go home right away.

3. Present Participle.

In the following sentence we can easily imagine that the opening clause could be written as “Since he tied the knot”:

Since tying the knot, John oozes confidence.

4. Past Participle.

Finally, in this non-finite clause we do have a subject (“canal”), but a past participle (“frozen”) instead of a regular verb:

With the canal frozen over, I am skating to work.

It should be pointed out that it can be difficult to decide if something is a non-finite clause or just a phrase. The two overlap significantly, so it may depend on what grammatical function you are focusing. For example, in the sentence “I love skiing” it is generally better to treat “skiing” as a gerund that forms the core of a noun phrase. That makes more sense than treating it as an entire non-finite clause.

The main take-away is that if a non-finite verb (and surrounding words) functions like a dependent clause, then you may want to classify it as such.

Verbless Clauses

Another implied clause is one where the verb is missing:

With her ex-husband in jail, Mary felt free as a bird.

Most verbless clauses are missing some form of “to be.” We could easily write “When her ex-husband was in jail,” or even “With her ex-husband being in jail.”


The main thing to remember is that a clause normally has a subject and a verb. It can either be a complete sentence by itself (independent clause) or needs to be attached to another clause (dependent clause). Sometimes we also have clauses that are missing some elements (like verbs) or use a non-finite verb instead of a finite one. In our quizzes we will ignore these exceptions, but it is helpful to be aware of them.

The Structure of Clauses


In our first lesson on clauses we explained that every clause needs at least a subject and a verb. In addition, if a clause can be a sentence by itself then we call it an independent or main clause. If not, it’s a dependent or subordinate clause.

In this section we will look at the main ways in which a single clause is put together. These patterns apply to independent and dependent clauses.

Key Patterns

Subject + Verb

The simplest sentences contain at least a subject and a verb:

You drive.

They laughed.

In these examples the verbs are intransitive because they lack a direct object.

Subject + Passive Verb

The verb can also be in the passive voice:

A deal was made.

The Robinsons were shipwrecked.

Subject + Verb + Direct Object

If the verb is transitive, it can take a direct object. The direct object is the noun or pronoun that receives the action of the verb:

Jen boarded the double-decker bus.

Eugene and Quentin played hide and seek.

Subject + Verb + Indirect Object + Direct Object .

If the clause has a direct object, it can also have an indirect object. The indirect object is the noun or pronoun for or to whom the action is done:

He gave me a compliment. (to me)

Bob taught Gary some dance moves. (to Gary)

Indira bought her friend some flowers (for her friend)

Note that the preposition to or for is left implied.

Subject + Linking Verb + Subjective Complement

If your verb is a linking verb, it will be followed by a word that describes the subject. We call this word (and its modifiers) the subject complement.

Sometimes the subject complement is an adjective:

She seemed angry.

The trout tasted great.

At other times the complement is a noun:

Karen was a cheerleader.

The Oilers are a scrappy hockey team.

If you want the technical terms, we call these complements predicate nouns and predicate adjectives.

Subject + Verb + Direct Object + Objective Complement

If you’ve just read about the subject complement, you will be happy to know that the objective complement works the same way—the only difference being that it describes the direct object:

Sometimes the objective complement is an adjective:

The coach called the loss embarrassing.

Hannah found her dinner and her boyfriend cold.

At other times the objective complement is a noun:

Management named Cindy Rella the new coach.

The disaster left Jerry a nervous wreck.

There or It + Linking Verb + Subject

The final pattern inverts the regular order of the sentence:

There is hope.

It is a good sign.


The patterns found on this page will help you understand the structure or skeleton of individual clauses. Of course, when you read actual sentences these patterns will not show up as clearly. You will have to disregard phrases and modifiers that add colour to the sentence. With a bit of practice, however, you will be able to see how each clause is put together.



Whereas clauses are larger units that usually contain at least a subject and a verb, phrases are smaller parts of the sentence.

Sometimes they are essential to the structure of a clause (e.g., a noun phrase that functions as the subject), and sometimes they just provide some extra information (most prepositional phrases).

As we review the different types of phrases, please note that one phrase can include another. For example, we can categorize swimming in the ocean as a participial phrase (swimming is a present participle), even though it includes a prepositional phrase (in the ocean). At times a phrase can even be interpreted as a clause if it takes on a similar function.

Types of Phrases

Noun Phrase

A noun phrase is any noun or pronoun along with its modifiers:

The school children
Yesterday’s newspaper
An old and rusted slinky

Verb Phrase

A verb phrase is any number of verbs working together:

Had been sleeping
Will contact
May have written

Verb phrases often contain adverbs that change the meaning of the phrase:

Has never lost
May not trespass
Am always looking

As the last example shows, verb phrases may include verbals (looking is a present participle), but a verbal by itself is not a verb.

Prepositional Phrase

A prepositional phrase always starts with a preposition and ends with a noun or pronoun (and its modifiers) that is called the object of the preposition:

Through the wheat field

Preposition: through

Object of the preposition: the wheat field

Here are some more examples of prepositional phrases:

During the year
Despite complaints
In the summer

Verbal Phrases

There are three types of verbal phrases: participial phrases, gerund phrases, and infinitive phrases. Each is explained below.

Participial Phrase

Participial phrases start with either a present or past participle. Here are some examples of each.

Phrases with present participles:

Lounging by the pool
Chasing a butterfly
Watching silently

Phrases with past participles:

Struck by lightning
Driven to succeed
Loaned out

Gerund Phrase

A gerund phrase is a present participle (and its modifiers) that acts like a noun. It can take on a variety of jobs in the sentence. Here are a couple of examples:

Practicing helped a lot. (subject)
I love reading. (direct object)

Infinitive Phrase

An infinitive phrase is the infinitive and its modifiers:

To sing
To walk all that way
To mix peanut butter and jam

The infinitive phrase can also function in various ways:

To give to charity is a noble thing. (subject)

The neighbours have promised to stop playing the drums at night. (direct object)

Appositive Phrase

An appositive phrase is a phrase that renames an earlier noun or pronoun:

My best friend, Nick Palacio, loves scuba diving.
We watched Sirius, the brightest star in the sky.

In these examples, the appositive is a noun phrase. But you can use other phrases as appositives too:

My dream, to make it to the NBA, is what keeps me going. (infinitive phrase)

Matthew’s special talent, bouncing on his head on the trampoline, gives him a unique perspective on life. (participial phrase)

Appositives are great for inserting some extra information in a sentence.

Absolute Phrase

Absolute phrases are the trickiest to identify. These phrases are not closely connected to the rest of the sentence; they don’t describe a specific word, but modify the whole sentence. They add extra information and are usually separated by commas (or dashes).

At the heart of an absolute phrase you will find a noun or pronoun and some modifiers.

Very often the modifier is a participle:

The tide coming in, most beachgoers were packing up.

Absolute phrase: The tide coming in.

Here are some more examples:

The semester finished, Karen sold all her textbooks.

Absolute phrase: The semester finished.

The ice finally frozen over, we went skating.

Absolute phrase: The ice finally frozen over.

Another way to form an absolute phrase is to add an adjective to your noun or pronoun:

Her skin sweaty and hot, Tamara looked forward to having a shower.

Absolute phrase: Her skin sweaty and hot.

In many of these examples we could add the word being (Her skin being sweaty and hot), but you can usually do without.

You’ll also notice how close these phrases are to being a clause. All you have to do is add a conjunction and change the participle to a finite verb:

When the ice finally froze over, we all went skating.

Conjunction: When.

Finite verb: froze.

And the final thing to observe is that the absolute phrase can also come at the end of the sentence.

Sentence Classification


Once you know the difference between an independent clause and a dependent (or subordinate) clause, you can see the basic structure of each sentence. This page will teach you a few labels you can use to describe the various combinations of independent and dependent clauses.

Some teachers think these labels are essential. We disagree. The main thing is to know that clauses can be combined in some rather complex ways.

Sentence Types

Simple Sentence

A simple sentence consists of just one independent clause:

Mary had a little lamb.

Compound Sentence

A compound sentence consists of two independent clauses. These can be joined by a coordinating conjunction or a punctuation mark such as a semi-colon, colon, or dash:

Mary had a little lamb | and | its wool was white as snow.

Mary had a little lamb | ; | its wool was white as snow.

Mary had a little lamb | — | she kept it for its wool.

Complex Sentence

A complex sentence consists of one independent clause and any number of dependent clauses:

Wherever Mary went, | the lamb would go as well.

In this example, the first clause is dependent and the second is independent.

Compound-Complex Sentence

Finally, a compound-complex sentence consists of two independent clauses and any number of dependent clauses:

Although the children loved the lamb, | the teacher disapproved of lambs | so | she told Mary to take it home.

In this example, the first clause is dependent, whereas the last two (joined by a coordinating conjunction) are independent.