Lesson 9

Compound & Complex Sentences

For confident learners: joining clauses to express more complex ideas.

A Note on Scope

This lesson is for confident learners

Compound and complex sentences are not essential for beginners or lower-intermediate learners. Before going further, make sure you are comfortable with the previous lessons.

Writing clearly does not require compound or complex sentences. Two simple sentences can communicate just as well:

It started to rain. So they called off the picnic.  (informal)
It started to rain. Therefore, they called off the picnic.  (formal)
They called off the picnic because it started to rain.  (complex sentence)

All three communicate the same idea. However, native speakers use compound and complex sentences naturally, so this is worth knowing.

Clauses

A clause is simply a group of words that contains a subject and a verb. There are two types:

Independent clause

A clause that can stand alone as a complete sentence.

A bad accident happened yesterday.  (clause and sentence)

Dependent clause

A clause that has a subject and verb but cannot stand alone — it needs another clause to complete it.

because the man drove too fast.  (clause only — sounds incomplete)

Remove the word "because" and it works fine: The man drove too fast. The extra word makes it dependent — it needs to attach to another clause.

Complex Sentences

A complex sentence joins an independent clause with a dependent clause.

Because the heavy traffic delayed the man's arrival — something happened because of a delay???  (incomplete — more information needed)
The meeting was rescheduled, because the heavy traffic delayed the man's arrival.  (complete complex sentence)

More complex sentences

Marked as: subject, verb, object (D.O.)

Because it was raining, we decided to stay inside and read books.
She enjoys swimming even though the water is cold.
Although she was tired, she continued to work on the project.
Since it was his birthday, he received many presents.
He went to the library so he could borrow some books.
After he had lunch, he went back to the office.
She was excited because she had won the competition.
If you finish your work, you can join us for dinner.
Before he left for work, he made sure to lock the doors.
She went for a walk in the garden after she finished her meal.
Although it was a long journey, they enjoyed every moment.
She drank a lot of coffee while she was studying for the exam.
Since she loves animals, she decided to become a veterinarian.
He went to bed after he finished his homework.
After they watched the movie, they discussed it for hours.
She was happy because she had finally found her keys.

Compound Sentences

A compound sentence joins two complete, independent sentences together using a coordinating conjunction.

FANBOYS — the seven coordinating conjunctions

For  ·  And  ·  Nor  ·  But  ·  Or  ·  Yet  ·  So
She wanted to go for a walk, but it started raining.
I love chocolate, and I eat it every day.
The sun was setting, and the sky looked beautiful.
I was tired, but I couldn't fall asleep.
The car broke down, so we had to walk home.
They were exhausted, yet they continued to work.
She bought a new dress, and she wore it to the party.
We went to the beach, and we had a great time.
I called my friend, but she didn't answer.
They were running late, but they managed to catch the bus.
He loves hiking, and he goes to the mountains every weekend.
She is very talented, and she plays the piano beautifully.
The weather was perfect, so we decided to have a picnic.
I wanted to go to the gym, but it was closed.
She loves painting, and she spends hours in her studio.
We went shopping, and then we had lunch at a cafe.
The movie was boring, but the book was interesting.
She was singing, and everyone was listening quietly.
He missed the train, so he had to wait for the next one.
We visited the museum, and we learned a lot.