What is Compound-complex Sentence and How to Write One?

In English, we categorize sentences into four types on the basis of their structure (number of dependent and independent clauses): simple, compound, complex, and compound-complex. Using different types of sentences adds variety to our writing, with the latter three combining multiple ideas to convey complex message.

In this post, we’ll cover compound-complex sentence.

Learn the other three types:

What is a compound-complex sentence?

A compound-complex sentence is a sentence that contains at least two independent clauses and at least one dependent clause. Of the four types of sentences, it has the maximum number of minimum-required clauses, three. With minimum of three clauses, they carry quite complex information in a single sentence while adding variety to your sentences. When used in moderation, such sentences leave a positive impression about your ability to weave multiple pieces of information in a tight relationship.

Here is a brief summary of number of dependent and independent clauses in the four types of sentences.

Number of dependent and independent clauses in compound-complex sentences (tabular form)

Note: Feel free to use the above and other images in the post, using the link (url) of this post for reference/attribution.

If you notice, a compound-complex sentence is essentially a hybrid of a compound and a complex sentence, retaining best of both the worlds: taking ‘at least one dependent clause’ from complex sentence and ‘at least two independent clauses’ from compound sentence (shown in the above image through arrows).

And here is the same information in graphical form, which will make it abundantly clear that there is no overlap between the four types of sentences (none of the dots cross paths).

Number of dependent and independent clauses in compound-complex sentences (graphical form)

Although most use adverb clause as the dependent clause when writing compound-complex sentences, the dependent clause can also be noun clause, relative clause, or a mix of three. Each of these examples contain exactly two independent clauses and 1-2 dependent clauses (underlined).

Everyone has a different perception of normal, and when someone breaches that boundary, discrimination is not far. [Adverb clause]

People say that tigers are regular to the hilltop pond at night, and some have reportedly seen them. [Noun clause]

The world is undergoing an unstoppable climate change, whose effects are visible in the form of extreme hot and cold events in several geographies, but we continue to look the other way. [Relative clause]

Reality shows are platforms where people aren’t discriminated, for the only thing that matters is what you bring to the table. [Relative clause/ Noun clause]

Results are tough to predict this year, but if the company continues to innovate and launch new products, the stock, which hasn’t really lived up to the high expectations of investors in 2021, can perform well. [Adverb clause/ Relative clause]

See more examples of compound-complex sentences:

We’ll see how they’re written and punctuated later in the post.

How to write a compound-complex sentence?

A compound-complex sentence contains at least three clauses. Which clause should you write first? Should you first write the independent clauses, which express main ideas in the sentence?

The answer is simple: Don’t go by clauses; go by chunks or thoughts. A chunk may contain one or two clauses. Let’s take an example.

The two natural chunks for a sentence I plan to write are:

Enjoy the flattery you receive. [Chunk 1]

Don’t believe it because people often flatter to meet their own selfish interests. [Chunk 2]

The second chunk contains two clauses. There is no point in writing three chunks, with each containing a clause, if each doesn’t form a complete thought. You can now combine them like you combine independent clauses to form a compound-complex sentence.

Enjoy the flattery you receive, but don’t believe it because people often flatter to meet their own selfish interests.

If you don’t understand the punctuation in the above sentence, refer the next section. Another example:

If you ask to repay, he may feel offended. [Chunk 1]

If he fails to repay, you’ll be offended. [Chunk 2]

If you ask to repay, he may feel offended, and if he fails to repay, you’ll be offended. [Compound-complex sentence = Chunk 1 + Chunk 2]

Yet another example:

Results are tough to predict this year. [Chunk 1]

If the company continues to innovate and launch new products, the stock can perform well. [Chunk 2]

The stock hasn’t really lived up to the high expectations of investors in 2021. [Chunk 3]

Results are tough to predict this year, but if the company continues to innovate and launch new products, the stock can perform well. [Chunk 1 + Chunk 2. Even this is a compound-complex sentence]

Results are tough to predict this year, but if the company continues to innovate and launch new products, the stock, which hasn’t really lived up to the high expectations of investors in 2021, can perform well. [Compound-complex sentence = Chunk 1 + Chunk 2 + Chunk 3. Chunk 3 has been added as a relative clause to the previous step]

Your chunks maybe different from these, and that’s fine. There can be more than one way to arrive at the same sentence. There is an exercise on forming compound-complex sentences, by using chunks, later in the post.

Punctuation in compound-complex sentences

Most learn punctuation in compound-complex sentences assuming that they contain only adverb clause as the dependent clause. But, as we saw earlier, these sentences can also be formed with noun clause and relative clause or any combination of three. We’ll consider punctuation with all three types of dependent clauses. Let’s start with the most-used dependent clause in compound-complex sentences, adverb clause.

1. Punctuation with adverb clause

Step 1: Put a comma before coordinating conjunctions if a sentence follows them

You can adopt any of the two; they’re one and the same.

1. Find coordinating conjunctions (FANBOYS) in the sentence. Is it followed by a complete sentence? (I’ve used the term ‘sentence’ and not ‘independent clause’ for a reason, which I’ll delve into in a while.) If yes, put a comma before it, like you do in compound sentences.

2. Find coordinating conjunctions (FANBOYS) in the sentence. Put a comma before them if they’re not joining words or phrases or dependent clauses.

Step 2: Punctuate adverb clause like you do

Now punctuate adverb clauses like you normally do:

1. When an adverb clause begins a sentence, a comma is always used to separate it from the independent clause.

2. When an independent clause begins a sentence, a comma is rarely used to separate it from the adverb clause.

 3. When an independent clause begins a sentence, comma is acceptable where the adverb clause expresses contrast with the independent clause. Such contrast is often expressed by subordinating conjunctions although and even though.

Examples of punctuating compound-complex sentences with adverb clause

I’ve seen many pick up punctuation in compound-complex sentences through a methodical process like the above. Let’s take few examples of unpunctuated compound-complex sentences. In the first sentence, the adverb clause is the third clause after the two independent clauses; in the second, it is second; and in the third, it is first. In the fourth sentence, one of the independent clauses comes with an introductory phrase, which requires its own comma. In the fifth, there are three independent clauses.

Example 1: I am well aware of the challenge but I am determined to put in the hard work till I achieve my goal.

Step 1: A sentence (I am… my goal) follows but, implying a comma before but.

I am well aware of the challenge, but I am determined to put in the hard work till I achieve my goal.

Alternatively, but doesn’t join two words or phrases, implying a comma before but.

Step 2: The adverb clause (till I achieve my goal) follows the independent clause (I am… hard work) on which it is dependent; hence, it won’t take comma.

I am well aware of the challenge, but I am determined to put in the hard work till I achieve my goal.


Example 2: I have applied online on your website but if it makes it easier for you I am also sending resume and cover letter through this email.

Step 1: A sentence (if it… this email) follows but; hence, we put a comma before but. If I had used ‘independent clause’ instead of ‘sentence’, there was no independent clause in this case immediately after but. But sentences, yes!

I have applied online on your website, but if it makes it easier for you I am also sending resume and cover letter through this email.

Step 2: The adverb clause (if it makes it easier for you) comes before the independent clause (I am also… this email) on which it is dependent; hence, the dependent clause will be followed by comma.

I have applied online on your website, but if it makes it easier for you, I am also sending resume and cover letter through this email.


Example 3: Because a noun clause functions exactly like a noun you can replace it with a noun or pronoun and the sentence will still make grammatical sense.

Step 1: A sentence (the sentence… grammatical sense) follows and; hence, we put a comma before and. Note that the other coordinating conjunction, or, coincidentally has a sentence after, but or here is part of the phrase noun or pronoun.

Because a noun clause functions exactly like a noun you can replace it with a noun or pronoun, and the sentence will still make grammatical sense.

Step 2: The adverb clause (Because… like a noun) comes before the independent clause (you can… or pronoun) on which it is dependent; hence, the dependent clause will be followed by comma.

Because a noun clause functions exactly like a noun, you can replace it with a noun or pronoun, and the sentence will still make grammatical sense.


Example 4: We like clothes more when they’re new but with relationships it’s the other way round.

Step 1: A sentence (with… way round) follows but. Hence, we put a comma before but. Also, with relationships is an introductory phrase before the main clause it’s the other way round, and it requires a comma to separate it from the main clause.

We like clothes more when they’re new, but with relationships, it’s the other way round.

Step 2: The adverb clause (when they’re new) comes after the independent clause (We like clothes more) on which it is dependent. Hence, it won’t take comma

We like clothes more when they’re new, but with relationships, it’s the other way round.


Example 5: The group of words itself doesn’t have a subject and that’s why it’s not a clause but if we expand the group to the entire sentence it’ll correspond to the subject.

Step 1: A sentence (that’s why… the subject) follows and, hence we put a comma before and. A sentence (if we expand… the subject) follows but; hence, we put a comma before but.

The group of words itself doesn’t have a subject, and that’s why it’s not a clause, but if we expand the group to the entire sentence it’ll correspond to the subject.

Step 2: The adverb clause (if we expand… entire sentence) comes before the independent clause (it’ll… the subject) on which it is dependent; hence, the dependent clause will be followed by comma.

The group of words itself doesn’t have a subject, and that’s why it’s not a clause, but if we expand the group to the entire sentence, it’ll correspond to the subject.

Learn more about punctuation when joining an adverb clause to an independent clause:

2. Punctuation with noun clause

Punctuate independent clauses just like you did in the first step of adverb clause. For the noun clause, you may follow this process.

Because a noun clause simply takes the place of a noun or pronoun, it doesn’t require any additional punctuation – comma or dash – as is the case with other two dependent clauses. If a noun, noun phrase, or pronoun in its place doesn’t require a comma, a noun clause too won’t. Examples:

The researchers measured how long the mice spent in searching the way out of the tunnel, and did it remember the escape route. [Two independent clauses and a noun clause]

The researchers measured its pulse rate, and did it remember the escape route. [The replacement doesn’t require any comma, implying a noun clause in its place too won’t.]

The loss to Australia raises the question of who plays in the next match and what will be the role of coach, but will that reverse the team’s fortunes. [Two independent clauses and two noun clauses]

The loss to Australia raises the question of competence and coach’s role, but will that reverse the team’s fortunes. [The replacements don’t require comma, implying noun clauses in their place too won’t.]

3. Punctuation with relative clause

Punctuate independent clauses just like you did in the first step of adverb clause. For the relative clause, you may follow this process.

When a relative clause is essential to the meaning of the noun being described, it carries no comma. In the example below, without the relative clause, we wouldn’t know what kind of platforms they are (in other words, some meaning will be lost). Hence, it’s essential and doesn’t take any commas.

Reality shows are platforms where people aren’t discriminated, for the only thing that matters is talent.

However, when a relative clause is not essential to the meaning of the noun being described, it is set off by a pair of commas. In the following example, even without the relative clause, we would know what climate politics is (in other words, no meaning will be lost). Hence, it’s non-essential and would take a pair of commas.

Climate politics, which has gathered steam in the light of recent extreme climatic events, has shifted in the last few years, and that gives us all hope.

Learn more about punctuation when joining a relative clause to an independent clause:

Exercises

Exercise 1: Punctuate compound-complex sentences

Punctuate the following compound-complex sentences with commas. The first three contain only adverb clauses as dependent clauses, and the fourth only noun clause.

1. If it rains tomorrow bring your umbrella or you might catch cold.

2. If you want to go quickly go alone but if you want to go far go together.

3. Don’t get into an argument or fight in the first place and if you do get into one get out of it at the earliest opportunity.

4. People generally believe that dogs are friendlier than cats but cats can also be extremely loving.

Answers to Exercise 1

1. If it rains tomorrow, bring your umbrella, or you might catch cold.

2. If you want to go quickly, go alone, but if you want to go far, go together.

3. Don’t get into an argument or fight in the first place, and if you do get into one, get out of it at the earliest opportunity.

4. People generally believe that dogs are friendlier than cats, but cats can also be extremely loving.

Exercise 2: Write compound-complex sentences

Combine the three clauses to form a compound-complex sentence. If one of the three is already not a dependent clause, you’ll have to convert one. You don’t have to combine them in the order they’re presented.

1. I’ll briefly touch upon last week’s lesson. You won’t understand some of today’s lesson. Before we start today’s class.

2. There are many problems in the company. We remain hopeful. A silent revolution is underway.

3. You better work hard to improve your academic standing. It’ll be challenging to get shortlisted for job interviews. The job interviews will be held next semester.

4. Dr. Johnson ate a big meal. He went to work afterward. He is known for his appetite.

Answers to Exercise 2

(Dependent clauses have been underlined.)

1. Before we start today’s class, I’ll briefly touch upon last week’s lesson. [Chunk 1]

You won’t understand some of today’s lesson. [Chunk 2]

Before we start today’s class, I’ll briefly touch upon last week’s lesson, or you won’t understand some of today’s lesson. [Compound-complex sentence]

2. There are many problems in the company, but we remain hopeful. [Chunk 1]

A silent revolution is underway. [Chunk 2]

There are many problems in the company, but we remain hopeful as a silent revolution is underway. [Compound-complex sentence]

3. You better work hard to improve your academic standing, or it’ll be challenging to get shortlisted for job interviews. [Chunk 1]

The job interviews will be held next semester. [Chunk 2]

You better work hard to improve your academic standing, or it’ll be challenging to get shortlisted for job interviews, which will be held next semester. [Compound-complex sentence]

4. Dr. Johnson ate a big meal, and he went to work afterward. [Chunk 1]

He is known for his appetite. [Chunk 2]

Dr. Johnson, who is known for his appetite, ate a big meal, and he went to work afterward. [Compound-complex sentence]

How to identify a compound-complex sentence?

Identifying a sentence as compound-complex is all about identifying the number of dependent and independent clauses in the sentence. If it contains at least two independent clauses and at least one dependent clause, it’s compound-complex. However, that’s easier said than done. Try identifying the types of these sentences.

Collision by an asteroid of even few hundred meters can cause apocalyptic harm to humans and the planet, so scientists are mapping each and every asteroid of significant size that could reach earth.

The law is same for both, but the rich, through their abundant resources, can get favorable decisions by influencing decision makers, hiring the best lawyers, and delaying the case if it suits them, among several measures at their command.

Both are compound-complex sentences, containing two independent clauses and one dependent clause. The dependent clauses are that could reach earth and if it suits them, respectively. Identifying dependent and independent clauses is a task in itself and can’t be covered in the limited space here.

Get better at identifying clauses in a sentence:

What implications do compound-complex sentences hold for your writing?

Learning how to write compound-complex sentences with correct punctuation will help you express complex ideas in a single sentence and write sentences of some length, adding variety to your writing. I’ve heard from students how, after mastering compound-complex sentences, they shed their fear of messing up on punctuation and other things and started writing long sentences.

Compound-complex sentences though are relatively less used than complex and simple sentences in professional writing, one likely reason being multiple main ideas because of multiple independent clauses. (Remember, an independent clause expresses the main idea of a sentence, with the dependent clauses chipping in with less important ideas.) One main idea per sentence is ideal for readers, which is achieved by complex and simple sentences.

What’s the implication of this?

Use compound-complex sentences by all means, but expand your repertoire of complex sentences, especially those with relative and noun clause, and simple sentences, especially those with variety of phrases. Most don’t tap into their full potential.

Second, avoid more than two independent clauses as three main ideas in a sentence are too many.

Frequently Asked Questions

Can a compound-complex sentence have 3 independent clauses?

Yes. A compound-complex sentence contains at least two independent clauses, implying it can have three.

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