What Are Complex Sentences?

A complex sentence is a sentence that has a main clause and one or more finite dependent clauses attached to it.

Main vs. Dependent Clauses

Main clauses are independent and determine the tense and the subject of the whole sentence and can form a sentence on their own, but dependent clauses cannot stand alone, even though they have a subject and a verb; they are connected to the main clause and form part of the complex sentence.

Example

when I arrived at the airport → dependent clause

I was a happy kid. → independent clause

How to Identify a Complex Sentence?

To identify a complex sentence you can look for a finite dependent clause, that is, a subordinate clause, a that-clause, or a relative clause which is connected to a main clause using a subordinating conjunction, a relative pronouns or relative adverbs, or "that".

Subordinate Clauses

Subordinate clauses are introduced by subordinating conjunctions which are words that are used to link a dependent clause to its main clause. These clauses act as adverbs. The most common subordinating conjunctions are:

Example

Even though he is 31, he still acts like a little child.

Michael studied law because he wanted to become a lawyer.

Joining Clauses Together

When a subordinate clause joins a main clause to form a complex sentence, the sentence can have two structures:

the main clause comes first:

Example

I was snippy with him because I was running late for work.

the subordinate clause comes first:

Example

Because I was running late for work, I was snippy with him.

As you can see in the examples, if the subordinate clause comes first, the clauses are separated using a comma. However, if the main clause comes first, there is no need for a comma.

That-clauses

That-clauses are also finite dependent clauses that function as noun and can act as subjects, objects, or complements for the main clause to form complex sentences. Look at the following examples:

Example

I know that you are busy.

"that you are busy" acts as the object of the main clause

The truth is that we lost the game.

"that we lost the game" acts as a complement for the main clause

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Relative Clauses

Relative clauses can also be embedded into a main clause to form a complex sentence. These clauses are introduced by relative pronouns or adverbs and act as adjectives for nouns in the main clause. Here are some examples:

Example

I saw a dog that was chasing a ball.

"that was chasing a ball" is a relative clause which is independent and modifies the noun "dog".

The woman who lives next door is my teacher.

Here, "The woman is my teacher" is the main clause and "who lives next door" is a dependent clause embedded into the main clause.

Nominal Relative Clauses

Nominal relative clauses are also introduced by relative pronouns or adverbs, but they function as nouns in sentences. These clauses act as the subjects, objects, or complements of the main clause in complex sentences. Here are some examples:

Example

What you said makes sense.

Here, "what you said" acts as the subject of the main clause.

I don’t understand what she wants.

In this sentence, the nominal relative clause "what she wants" acts as the objects of the main clause "I don't udnerstand".

Conditional Sentences

One of the most common types of complex sentences are conditional sentences. These sentences talk about hypothetical situations, often using 'if' or 'unless' as condition markers.

Example

If you want to be a successful businessman, you have to understand the language of trade.

The baby won't go to sleep unless I tell him a bedtime story.

Compound Sentence vs. Complex Sentence

Complex sentences are similar to compound sentences, with only one difference: compound sentences have two independent clauses, but complex sentences have one independent and one or more dependent clauses.

Review

'Complex sentences' are formed using a finite dependent clause attached to a main clause. The only difference between compound and complex clauses is that compound clauses are made up of two independent clauses.

Here are some examples of complex sentences.

Example

Although I am not good at it, I enjoyed playing basketball with John.

Since she left me, I decided to raise our child on my own.

Quiz:


1.

Which of the following is a complex sentence?

A

I went to the store, and I bought some groceries.

B

I went to the store because I needed groceries.

C

I went to the store; I bought some groceries.

D

I went to the store, buying some groceries.

2.

Complete the table below by identifying whether each sentence is a complex sentence (Yes) or not (No).

I forgot that he was coming to visit.

I wanted to go to the beach, but it started raining.

Until the rain stops, we can’t leave the house.

The problem is that they didn’t finish the task.

They went to the park to take a walk.

Although it was raining, we went for a walk.

No
Yes
3.

Sort the words to form a grammatically correct complex sentence.

he
missed
because
meeting
,
was
he
.
sleeping
the
4.

Match the sentences with the type of dependent clause they contain.

Although she practiced hard, she didn’t win the race.
The artist who painted this mural lives downtown.
He admitted that he forgot the keys.
Where we go next depends on the weather.
Subordinate clause
Nominal relative clause
Relative clause
That-clause
5.

Fill in the blanks with the correct words. (There are two extra options.)

I missed my bus, I arrived at work on time.

She didn’t go to the party

she wasn’t feeling well.

I don’t know

he didn’t come to the meeting.

The book

I borrowed was fascinating.

you don't practice, you won't improve.

even though
because
why
that
if
what
unless

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