What is a sentence?

In this chapter, we will look at what comprises a sentence. We will explore the elements used to construct sentences, and what parts of speech are used to expand and elaborate on them.
We will focus for now on forming simple sentences (sentences that contain only a single independent clause). In the subsections of this chapter, we will explore the different kinds of sentences according to structure, purpose, and length.

The Construction of a Sentence


In English, a clause almost always consists of two parts—a subject and a predicate. (This rule is only broken when making imperative sentences and non-finite clauses.) In traditional English grammar, a predicate is made up of a verb or verb phrase (a verb and any objects or modifiers relating to it), while the subject consists of a noun, pronoun, or a phrase containing either.
A sentence, whether short or long, must express a complete idea; and a complete sentence must consist of at least one independent clause—that is, a subject and predicate that make a complete thought. Independent clauses are so called because they make sense when they stand on their own. They are also sometimes referred to as “main clauses.”
For example:
  • “I refuse.”
  • “The wind blows.”
  • “Dogs bark.”
  • “Bees sting.”
  • “Cats meow.”
In the above examples, the subject begins the sentences and the predicate ends them. The predicate (in each these cases made up of just a verb) contains all the necessary information about the subject to be considered logical, so each is considered an independent clause.
A dependent clause, on the other hand, relies on the information from an independent clause to form a complete, logical thought. Dependent clauses (also known as subordinate clauses) are usually marked by dependent words, such as a subordinating conjunctions or relative pronouns. Here are some examples of dependent clauses:
  • whenever (subordinating conjunction) I travel”
  • whom (relative pronoun) we met on the plane”
We can see that the clauses above do not express a complete idea—they require independent clauses to be logically complete:
  • Whenever I travel, I like to stay in fancy hotels.”
  • “We struck up a great conversation with a person whom we met on the plane.”
For more information on independent and dependent clauses, see the chapter on Clauses.

Additional Information

Verb phrases add additional information to a sentence. Because verb phrases can be made up of more than one verb, as well as the information relating to those verbs, we can add quite a bit of information into a single sentence. This additional information is used to answer the questions Why?, What?, What kind?, When?, Where?, How?, How much?, and Who/Whom?
For instance, let’s look again at the very first example from above:
  • “I refuse.”
Now let’s add more information to create a verb phrase:
  • “I refuse to eat.”
Adding the infinitive phrase (“to” + the simple form of a verb) explains What? about the action of the main verb, “refuse.” It is considered the object of the verb; together they form a verb phrase, which constitutes the predicate.
We can continue to expand the predicate to include more information:
  • “I refuse to eat that awful food.”
The modifiers “that” and “awful,” together with the noun “food,” are the direct object of the verb “eat,” again answering the question What? All together, they form the object of “refuse,” providing us with more detailed information about exactly what “I” is refusing.
Let’s look at some examples where additional information answers various questions about otherwise basic sentences:
  • “The wind blows in the north.” (Identifying where the wind blows.)
  • “The train leaves at night.” (Identifying when the train leaves.)
  • “Electricity costs a lot.” (Here we state how much it costs.)
  • “Bees sting people.” (Here we state “who” they sting.)
  • “Dogs bark when they are hungry, happy, or angry.” (Here we state why or when they bark.)
  • “Cats meow because they want attention.” (Here we state why they meow.)
We can make sentences even longer by adding more information. For example:
  • “Electricity costs a lot during the day in most countries.”
Here we have added the answer to three questions:
  • How much? – “a lot”
  • When? – “during the day”
  • Where? – “in most countries”

Further elaboration

We can give even more details by adding adjectives, adverbs, and prepositional phrases. Remember, an adjective describes a noun whereas adverbs describe verbs, adjectives, or other adverbs. Prepositional phrases, on the other hand, can act as either adjectives or adverbs.
Let’s look at an example:
  • Solar-powered electricity rarely costs much during the day.”
Here we use the adjective “solar-powered” to describe the subject noun “electricity.” It answers the question, “What kind of electricity?”
We used “rarely,” which is an adverb of frequency, to describe the verb “cost;” likewise, the prepositional phrase “during the day” is used adverbially to describe the verb “costs” and answer the question When?
Although “much” can be used as an adverb, it is here used as an indefinite pronoun to be the direct object of the verb “cost.” Be careful with “much,” because it can function as a determiner (adjective before a noun), adverb, or pronoun, depending on the sentence.
Let’s look at another example:
  • Cold wind from the Atlantic Ocean blows in at night.”
  • The adjective “cold” and the prepositional phrase “from the Atlantic Ocean” both modify the subject “wind.”

Compound subjects

A sentence can also have multiple subjects that relate to the same verb; these are known as compound subjects. For example:
  • James and Daniel collaborated on the project together.”
“James” and “Daniel,” joined by the conjunction “and,” are both related to the verb “collaborate.” Each subject in a compound subject can be modified and expanded in the same ways that we’ve seen already:
  • My brother James and his colleagues from India collaborated on the project together.”
“James” is now modified by “my brother,” while the second subject “colleagues” is modified by “his” and “from India.”

Compound predicates

Likewise, a single subject can take multiple predicates that are joined by a conjunction, such as “and” or “or.” These are called compound predicates. For example:
  • “Janet runs, swims, and cycles.”
As with compound subjects, we can expand each of the compound predicate verbs individually:
  • “Janet runs in the morning, swims in the evening, and cycles to and from work.”

Restructuring the sentence

When forming simple sentences in English, the additional information included with the subject and the predicate can often be reordered. Information modifying the predicate can even appear before the subject, and vice versa.
It helps if we break down each element in the sentence into what question it is answering. Take a look at the sentences below for an illustration of how such reconstructions might work:
When (at what time)?
He goes
by bus
to the movies
every Saturday
at 8 o'clock.
Now let’s reorder the information in the predicate (everything after the verb “goes”):
When (at what time)?
He goes
to the movies
at 8 o'clock
by bus
every Saturday.
As you can see, the sentence still makes logical sense, sounds fine, and retains all of the information it had before.
Now let’s restructure it to have part of the predicate come at the beginning of the sentence:
When (at what time)?
At 8 o'clock
every Saturday
he goes
to the movies
by bus.
It is also possible to have the subject come at the end of the sentence, especially when we begin a sentence with “there is/are,” as in the popular English proverb:
  • “There is more than one way to skin a cat.”

Types of sentences

So far what we have been discussing are known as simple sentences, which are made up of a single independent clause and no dependent clauses. Even as we have added a lot of information into the sentences above, each one has remained an independent clause because each one has a subject (or compound subject) and a predicate.
However, there are many different types of sentences, depending on how we order the text, if we use multiple clauses, if we’re asking a question, etc. In the chapter sections below, we’ll begin looking at the various kinds of sentences we can make and how they are formed.

Classifications of Sentences

By Structure

In addition to simple sentences, which we learned about above, sentences classified by structure include:

By Purpose

The purpose of a sentence also determines its classification. The sentences classified by purpose are:

By Length

Similar to sentences classified by structure, sentences can also be classified by length:
  • Major/regular sentences
  • Minor/irregular sentences

1. What must a sentence contain in order to be complete? (Choose the answer that is most correct.)

2. Which of the following is not an independent clause?

3. What can a prepositional phrase modify in a sentence?

4. Where can a predicate appear in a sentence? (Choose the answer that is most correct.)

Chapter Sub-sections

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