Simple, Compound + Complex Sentences in English

Understanding the difference between the main sentence types in English will benefit your speaking AND writing skills.

This guide will help you learn how to use simple, compound, and complex sentences – which are key elements of English grammar.

Contents

Simple vs Compound vs Complex sentences

Simple sentences have only one subject and one verb.

On the other hand, compound and complex sentences have more than one subject and more than one verb.

Sentence Types	Examples
Simple = subject + verb	The sun rises. = 1 main idea
Compound = subject + verb (conjunction) subject + verb	The sun rises, and the birds sing. = 2 main ideas
Complex = (conjunction) subject + verb subject + verb	When the sun rises, the birds sing. = 1 supporting idea + 1 main idea

Simple sentences

A simple sentence has just one independent clause with ONE subject and ONE verb.

Example: Kim reads every morning. (One idea, complete on its own.)

Or even:

Kim reads.

We can also make simple sentences with groups of nouns:

Kim, Mike and the other guys read every morning.

Compound sentences

A compound sentence is really just two simple sentences (clauses) joined together. Compound sentences have TWO subjects and TWO verbs.

A compound sentence joins two independent clauses with a coordinating conjunction (and, but, or, so) between the clauses.

Example: Kim reads every morning, AND she writes in the evening. – Two standalone clauses connected by a conjunction (and).

And again, if we want, we can use groups of nouns (compound nouns) in compound sentences as well. We still have two subjects, two verbs and one coordinating conjunction:

Example: Kim, Mike and the other guys read every morning, BUT Jake, Ali and his friends just watch TV.

TIP: When writing, remember that we need a comma before a coordinating conjunction if it is followed by a subject!

Which conjunctions for compound sentences?

Many (traditional) teachers may tell you that you can make compound sentences using up to 7 conjunctions.

According to their FANBOYS model, the 7 conjunctions you need are: For, And, Nor, But, Or, Yet, So. .

However, there are some problems with this model:

For (meaning “because”) is only rarely used as a conjunction in everyday English conversation and writing:
e.g. “I have to come to see you for I have a favour to ask”.
No one in any English speaking country has said this for at least 100 years.
Yet (meaning “but” – with surprise) is rarely used alone in compound sentences.
We do still use “yet” as a conjunction, but nowadays, we usually put “and” before it:
e.g. “I told him three times not to call, and yet he kept on calling”.
Nor is more common than for and yet, though we only really use nor in formal contexts.
Instead of nor, people prefer to use negative + either:
e.g. “He didn’t say thanks, and he didn’t pay for it, either.” (This is a compound sentence with “and”, by the way!)
-Compound sentences with nor also have an unusual structure that we tend to avoid:
e.g. “He didn’t say thanks, nor did he pay for it”. (That’s right – you need a question form!). Ignore!

So, Or, But, And (SOBA)

In my opinion, you only really need 4 conjunctions to make compound sentences: So, Or, But, And (SOBA).

These four words are the most common – and the most useful – conjunctions you need to build compound sentences in most modern-day English speaking / writing situations.

Here are the SOBA conjunctions in more detail:

Conjunctions (SOBA)	Function	Example
and	Addition	I drink tea, and I drink coffee.
but	Contrast	I drink tea, but I don’t drink coffee.
or	Choice	I could make some tea, or we could go for a drink.
so	Result	I felt thirsty, so I had some tea.

Complex Sentences

A complex has TWO subjects and TWO verbs.

Complex sentences contain one main idea and one supporting idea.

The supporting idea always comes after a subordinating conjunction, e.g. because, although, since, etc.

“If” sentences are examples of complex sentences:

“If you stay out too late, you’ll turn into a pumpkin.”

– If you stay out tonight = conjunction + supporting idea
– You’ll turn into a pumpkin = main idea (complete thought)

This example uses because instead of if:

She reads every morning because it relaxes her. (She reads every morning = main idea) / because it relaxes her = dependent clause)

You can also switch the order of the clauses. In writing, when the dependent clause comes first, you need to use a comma:

Because it relaxes her, she reads every morning. (Same meaning, different order.)
Although he was tired, he continued working. (Contrast first, result second.)

Other examples:

If you study hard, you will succeed. (Condition first.)
You will succeed if you study hard. (Condition second.)

Which conjunctions for complex sentences?

We use subordinating conjunctions like because, if, unless, until, as long as, etc in complex sentences. Each subordinating conjunction has a different function:

Conjunction	Function	Example
Because	Reason	I went home because* I was tired.*
Although	Contrast	Although she felt cold, she went outside.
Since	Time/Reason	Where have you been since I saw you last?
When	Time	When it rains, it really rains!
If	Condition	I’ll be here if you need me!

Compound / complex sentence mistakes to avoid

Error Type	Incorrect Example	Correction
Run-on Sentence	She reads she writes.	She reads, and she writes.
Fragment	Because she reads.	She knows a lot because she reads.
Comma Splice	She reads, she writes.	She reads; she writes. /She reads, and she writes.

Different Sentence Types in Context

Model dialogue

This short conversation includes simple, compound, and complex sentences in a natural context.

A: What are you doing this weekend?
B: I’m going to the lake. (Simple)
A: That sounds relaxing (Simple). Do you go there often?
B: Yeah, I do actually. I like the quiet vibe there, and I always bring a book with me. (Compound)
A: Nice! I’ll come along too some time if I manage to finish my work. (Complex)
B: Perfect! Let me know when you’re free. (Complex)

A longer, formal text

This example includes a mix of sentence types.

I believe success comes from hard work. (Simple) Some people think you need to be lucky, but I think effort is more important. (Compound) Although it’s not easy, you can reach your goals if you try your best.

(Complex) As long as you keep learning, you will improve. (Complex) I often make mistakes, but I learn from them. (Compound) Because I practice every day, I feel more confident. (Complex)

When I need help, I ask my teacher. (Complex).

Although many people believe luck plays a major role, I would argue that dedication matters more. (Complex) Unless you commit to your goals, progress will be slow. (Complex)

As long as you continue to learn and adapt, you increase your chances of achieving something meaningful. (Complex) Some people wait for the perfect moment, but those who act—even when conditions aren’t ideal—often make more progress.

(Compound-complex) Because the world is competitive, we must not only work hard but also think critically. (Complex)

Make your own sentences

Complete each sentence using your own ideas. Try to vary the topics and include realistic vocabulary.

I wanted to go, but…
She likes working late, so…
Although I see my son often, I…
As long as you follow the instructions, you…
Because she was late, we…
When I arrived, I…
I enjoy cooking, but…
He missed the bus, so…
Although it was raining, they…
If we leave now, we…
Unless you hurry, you…

Practice: simple, compound, complex sentences

Exercise 1 – Identify the Sentence Type

Label each as Simple (S), Compound (C), or Complex (CX):

She walked to the store.
I wanted to go out, but it was raining.
Although he was tired, he finished the project.
The children played in the garden.
She missed the bus, so she took a taxi.
If you study hard, you will pass the test.
He enjoys cycling, but he doesn’t like running.
Since we moved here, I’ve felt more relaxed.

Exercise 2 – Fix the Sentence

Correct these errors:

They laughed they cried.
When I see him.
She speaks French, she writes in Spanish.
Although he was tired.
I enjoy reading I don’t like writing.
Because the exam was hard.
She likes music, she hates dancing.
Unless we leave now.

Exercise 3 – Complete the Sentences

Use the conjunction in brackets to complete the sentence.

I stayed inside ___ it was snowing. (because)
We can go to the park, ___ we need to finish our work first. (but)
___ the bell rings, we will leave. (When)
I’ll help you ___ you ask nicely. (if)
He didn’t come ___ he was sick. (because)
___ I arrived, they had already started. (When)
She kept going ___ she was tired. (although)
We’ll wait here ___ you get back. (until)

Answer Key

Exercise 1

Simple
Compound
Complex
Simple
Compound
Complex
Compound
Complex

Exercise 2

They laughed, and they cried.
When I see him, I’ll wave.
She speaks French; she writes in Spanish.
Although he was tired, he kept working.
I enjoy reading, but I don’t like writing.
Because the exam was hard, many students struggled.
She likes music, but she hates dancing.
Unless we leave now, we’ll be late.

Exercise 3

because
but
When
if
because
When
although
until