Clauses and phrases: the building blocks
Sentences are built from groups of words. Two of the most important groups are clauses and phrases. Knowing the difference helps you write complete sentences, avoid fragments and build more interesting writing.
The key question is simple: Does the group of words have a subject and a verb?
- The subject is who or what the sentence is about.
- The verb tells what the subject does or is.
If a group of words has both, it is a clause. If it is missing one or both, it is a phrase.
What is a phrase?
A phrase is a group of words that work together, but it does not have both a subject and a verb. A phrase cannot be a sentence on its own.
- in the morning
- the tall green tree
- running down the hill
- after the game
These are all useful pieces, but none of them says a complete thing. After the game … what happened?
Kinds of phrases
| Type | What it does | Example |
|---|---|---|
| Noun phrase | a noun and its describing words | the friendly brown dog |
| Verb phrase | a main verb and its helpers | has been sleeping |
| Prepositional phrase | starts with a preposition | under the bridge, with my friends |
| Adjective phrase | describes a noun | full of water |
| Adverb phrase | tells how, when or where | very carefully |
A prepositional phrase is the most common. It starts with a word like in, on, under, over, after, before, with or across.
What is a clause?
A clause has both a subject and a verb.
the dog barked — subject: dog, verb: barked
There are two main kinds of clauses.
Independent clauses
An independent clause expresses a complete thought. It can stand alone as a sentence.
- The baby laughed.
- We ate pizza.
- Our team won the game.
Dependent clauses
A dependent clause has a subject and a verb, but it does not express a complete thought. It depends on an independent clause to finish the idea.
- because it was raining
- when the bell rang
- if you finish your homework
Each one leaves you waiting: When the bell rang … what happened?
Dependent clauses start with words such as because, when, if, although, since, while, after, before, unless and until. These words are called subordinating conjunctions.
Putting them together
Clauses and phrases combine to make sentences.
After lunch (phrase), we played outside (independent clause).
Because it was raining (dependent clause), we played inside (independent clause).
The girl in the red coat (noun phrase with a prepositional phrase) waved at us.
Clause or phrase? A quick test
Ask:
- Is there a subject? (Who or what?)
- Is there a verb? (What is happening?)
- If both, does it make a complete thought by itself?
| Words | Subject? | Verb? | Type |
|---|---|---|---|
| on the shelf | no | no | phrase |
| the cat slept | yes | yes | independent clause |
| while the cat slept | yes | yes | dependent clause |
| sleeping on the shelf | no | no (an -ing word alone is not a full verb) | phrase |
Commas with dependent clauses
When a dependent clause comes first, put a comma after it.
When the movie ended, we went home.
When it comes after the independent clause, you usually do not need a comma.
We went home when the movie ended.
Common mistakes
- Writing a phrase as a sentence. In the morning. is a fragment. Fix it: In the morning, we went fishing.
- Writing a dependent clause alone. Because I was tired. is a fragment. Fix it: I went to bed early because I was tired.
- Thinking an -ing word is always a verb. Running fast has no subject and no full verb. She was running fast is a clause.
Try it yourself
Label each as a phrase, an independent clause or a dependent clause:
- under the table
- the bird sang
- although it was late
- with a big smile
- if we hurry
Then join number 5 to an independent clause to make a full sentence.
Answers: phrase, independent clause, dependent clause, phrase, dependent clause. Example: If we hurry, we will catch the bus.
Quick recap
- A clause has a subject and a verb; a phrase does not have both.
- An independent clause can stand alone as a sentence.
- A dependent clause starts with a word like because or when and needs an independent clause.
- Put a comma after a dependent clause that begins a sentence.