Syntax - English sentence structure

Introduction: This page contains some basic information about sentence structure (syntax) and sentence types. It also includes examples of common sentence problems in written English. ESL students who understand the information on this page and follow the advice have a better chance of writing well. [Note to teachers/advanced students]

Definition: Linguists have problems in agreeing how to define the word sentence. For this web page, sentence will be taken to mean: 'a sequence of words whose first word starts with a capital letter and whose last word is followed by an end punctuation mark (period/full stop or question mark or exclamamtion mark)'. On the basis of this definition, some of the sentences written by ESL students (indeed by all writers) will be correct, and other sentences will be problematic. Good readers (English teachers, for example!) can quickly see the difference between a correct and a problematic sentence.

Subject/predicate: All sentences are about something or someone. The something or someone that the sentence is about is called the subject of the sentence. In the following sentences the subjects are shown in red. Note how the subject is often, but not always, the first thing in the sentence.

John often comes late to class.
My friend and I both have a dog named Spot.
Many parts of the Asian coastline were destroyed by a tsunami in 2004.
The old hotel at the end of the street is going to be knocked down to make way for a new supermarket.
Sitting in a tree at the bottom of the garden was a huge black bird with long blue tail feathers.
The grade 7 Korean boy who has just started at FIS speaks excellent English.
On Saturdays I never get up before 9 o'clock.
Before giving a test the teacher should make sure that the students are well-prepared.
Lying on the sofa watching old films is my favourite hobby.

The predicate contains information about the someone or something that is the subject. The example sentences above are shown again, this time with the predicate marked in green.

John often comes late to class.
My friend and I both have a dog named Spot.
Many parts of the Asian coastline were destroyed by a tsunami in 2004.
The old hotel at the end of the street is going to be knocked down to make way for a new supermarket.
Sitting in a tree at the bottom of the garden was a huge black bird with long blue tail feathers.
The grade 7 Korean boy who has just started at FIS speaks excellent English.
On Saturdays I never get up before 9 o'clock.
Before giving a test the teacher should make sure that the students are well-prepared.
Lying on the sofa watching old films is my favourite hobby.

Do a quiz on the subject and predicate.

Simple subject/predicate: As you can see from the example sentences above both the subject and the predicate can consist of many words. The simple subject is the main word in the subject, and the simple predicate is the main word in the predicate. The simple subject is always a noun/pronoun and the simple predicate is always a verb.

In the following sentences the simple subject is shown in red and the simple predicate is shown in green.

My ESL teacher speaks a little Russian.
The young girl with the long black hair fell from her bike yesterday in heavy rain.
At the back of the line in the cafeteria yesterday was a large brown dog with a yellow collar around its neck!
My friend and I are going on holiday together this year.
Your mother or your father must come to the meeting.
Sitting in a tree at the bottom of the garden was a huge black bird with long blue tail feathers.

From the last three examples sentences above you will notice that the simple subjects and simple predicates can be more than one word.

Advice: To write strong, clear sentences you must know who or what you are writing about (subject) and what you want to say about them or it (predicate). Your writing will be more interesting if the subject is not the first thing in every sentence you write.

Do a quiz to identify simple subjects and predicates.

Sentence types: One way to categorize sentences is by the clauses they contain. (A clause is a part of a sentence containing a subject and a predicate.) Here are the 4 sentence types:

Simple: Contains a single, independent clause.
- I don't like dogs.
- Our school basketball team lost their last game of the season 75-68.
- The old hotel opposite the bus station in the center of the town is probably going to be knocked down at the end of next year.

Compound: Contains two independent clauses that are joined by a coordinating conjunction. The most common coordinating conjunctions are: and, or, but, so.)
- I don't like dogs, and my sister doesn't like cats.
- You can write on paper, or you can use a computer.
- A tree fell onto the school roof in a storm, but none of the students was injured.

Complex: Contains an independent clause plus one dependent clause. (A dependent clause starts with a subordinating conjunction. Examples: that, because, although, where, which, since.)
- I don't like dogs that bark at me when I go past.
- You can write on paper, although a computer is better.
- None of the students were injured when the tree fell through the school roof.
Note: A dependent clause standing alone without an independent clause is called a fragment sentence - see below.

Compound-complex: Contains 3 or more clauses (of which at least two are independent and one is dependent).
- I don't like dogs, and my sister doesn't like cats because they make her sneeze.
- You can write on paper, but using a computer is better as you can easily correct your mistakes.
- A tree fell onto the school roof in a storm, but none of the students was injured although many of them were in classrooms at the top of the building.

Advice: Writing that contains mostly short, simple sentences can be uninteresting or even irritating to read. Writing that consists of mostly long, complex sentences is usually difficult to read. Good writers, therefore, use a variety of sentence types. They also occasionally start complex (or compound-complex) sentences with the dependent clause and not the independent clause. In the following examples the dependent clause is shown in red:

Although it was raining, we decided to go fishing.
If it doesn't rain soon, the river will dry out.
Because the road was icy and the driver was going too fast, he was unable to brake in time when a fox ran into the road in front of him.

Note: Sentences can also be categorized according to their function. [More]

Note: Independent clauses are also called main clauses. Dependent clauses are also called subordinate clauses.

Do a quiz to identify clause types. Do a quiz to identify sentence types.

Problematic 'sentences': To write a correct sentence, you need to have a good understanding of what a sentence is. Students who don't have this understanding, or don't take care, often include problem sentences in their writing. Native English speakers are just as likely to write problem sentences as ESL students. There are three main types of problem sentence:

Run-on sentences: These are two sentences that the writer has not separated with an end punctuation mark, or has not joined with a conjunction. (Click the following run-ons to see where they should be separated into two sentences.)
- I went to Paris in the vacation it is the most beautiful place I have ever visited.
- It's never too late to learn to swim you never know when you may fall from a boat.
- If you're going to the shops can you buy me some eggs and flour I want to make a cake.
- I like our new math teacher, she always explains the work very clearly.
- He was late to school again, his bus got caught in heavy traffic.
Advice: It is helpful to read your written work aloud. When you speak, you will make natural pauses to mark the end of your sentences or clauses. If there is no corresponding end punctuation mark in your writing, you can be almost certain that you have written a run-on sentence.

Sentence fragments: Fragment sentences are unfinished sentences, i.e. they don't contain a complete idea. A common fragment sentence in student writing is a dependent clause standing alone without an independent clause. In the each of the following examples the fragment is the second 'sentence', shown in red:
- I don't think I'm going to get a good grade. Because I didn't study.
- She got angry and shouted at the teacher. Which wasn't a very good idea.
- He watched TV for an hour and then went to bed. After falling asleep on the sofa.
- She got up and ran out of the library. Slamming the door behind her.
- I have to write a report on Albert Einstein. The famous scientist who left _____ to live in the _________.
- After riding my bike without problems for over a year, the chain broke. 40 kilometers from my house!
Advice: If your 'sentence' is a dependent clause, or it doesn't contain both a subject and a predicate, then it is not a proper sentence. You can often detect fragments if you read your writing backwards sentence by sentence, i.e. from the last sentence to the first one. You can usually correct a fragment by connecting it to the sentence before or after it.

Good writers, who have a full understanding of the sentence, occasionally choose to write a sentence fragment. So you may see sentence fragments in the fiction or even some of the non-fiction you read. As an ESL student, however, you should avoid fragments (except when writing your own creative stories).

Rambling sentences: A rambling sentence is a sentence made up of many clauses, often connected by a coordinating conjunction such as and, or, so.
- John usually gets up before 7 o'clock, but yesterday his alarm clock did not ring, so he was still asleep when his boss called him at 10.30 to ask where he was and tell him that he would lose his job if he was late again.
- Although the blue whale has been protected for over 30 years and its numbers are increasing, especially in the North Pacific, where whale hunting has been banned, it is still at risk of extinction as its habitat is being polluted by waste from oil tankers and its main food, the plankton, is being killed off by harmful rays from the sun, which can penetrate the earth's atmosphere because there is a huge hole in the ozone layer over Antarctica.
Advice: A rambling sentence is quite easy to spot. You have almost certainly written one if your sentence contains more than 3 or 4 conjunctions. If you read the sentence aloud and run out of breath before reaching the end of it, you have written a rambling sentence. If your sentence stretches over many lines of writing, you have certainly written a rambling sentence and most probably a run-on sentence too.
Unlike run-ons or fragments, rambling sentences are not wrong, but they are tiresome for the reader and one of the signs of a poor writer. You should avoid them.

Do a quiz to identify problematic sentences.

General advice: If you are not sure whether you have written a good, correct sentence, ask your teacher! And remember: The more you read in English, the better a writer you will become. This is because reading good writing provides you with models of English sentence structure that will have a positive influence on your own written work.

Note: Good writing consists not only of a string of varied, correctly-structured sentences. The sentences must also lead from one to the next so that the text is cohesive and the writer's ideas are coherent. For information on these two important concepts, go to the Language words for non-language teachers page and click on Cohesion.

There are links to more sentence identification and sentence building exercises on the Writing Index of this website.