Simple sentences can convey basic ideas, but you need complex sentences to communicate more detailed ideas or express the relationship between ideas. That’s why it’s important to learn how to form complex sentences. Chances are that you already create complex sentences without thinking about it. Knowing what a complex sentence is, how to form it, and why you need it will help you communicate your ideas more effectively. It’s a skill you’ll carry with you no matter what you do.

Parts of a sentence

Before you dive into learning about complex sentences, it’s important to become familiar with the types of sentences and what they’re called. Building a sentence is a lot like building a house: you can do it without knowing any of the names for the tools and materials you need, but your work will be more difficult. In the same way, you can build a sentence without knowing the names of the parts, but your work will be easier and more productive when you know them.

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Here are the names for all the sentence parts you’ll need:

These elements are the building blocks you need to create all sorts of sentences, including complex sentences. Are you ready? Let’s go!

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Types of sentence structure

Now that you’re familiar with the names of all the parts of the sentence, you can see how you can fit them together to create different types of sentences. Below is a list of the different kinds of sentences that you can construct. 

Here’s a quick guide to sentence types

Type of sentenceConstructionExamples
Simple sentence[independent clause]My dog was hungry.She already had breakfast.
Compound sentence[independent clause] + [coordinating conjunction] + [independent clause]My dog was hungry, but she already had breakfast.
Complex sentence[subordinating conjunction] + [dependent clause] + comma + [independent clause][independent clause] + [subordinating conjunction] + dependent clause]Even though she already had breakfast, my dog was hungry.
My dog was hungry even though she already had breakfast.
Compound-complex sentenceMany different types of construction. Two common ones are:1. [subordinating conjunction] + [dependent clause] + [comma] +  [independent clause] + [coordinating conjunction] + [independent clause]After my dog had finished her breakfast, she jumped on the couch and barked at me.

Knowing what kind of sentence you’re forming is the first step in learning how to improve your writing by creating complex sentences. It’s also true that you often create complex sentences without thinking about it. 

But if you want to improve your writing and make your ideas more apparent to others, learning how to craft a complex sentence is a good first step. It’s almost as important as working on your vocabulary. 

Why does this matter?

Now that you’ve explored types of sentences, you might be wondering, so what? Who cares what type of sentence I use? These are valid questions. The short answer is this: you need complex sentences because they allow you to express the relationship between ideas. 

Simple sentences have their uses, but it’s awkward to explain the relationship between them. Here is an example:

These two simple sentences both express a related idea. But it’s not immediately obvious what the relationship is. This is where compound and complex sentences come in:

Both the compound and the complex sentences above include the original ideas of the simple sentences, but they also explain the relationship between each idea. In this example, the relationship is one of cause-and-effect. There are other types of relationships between ideas. Here is another example:

The relationship between the two ideas above is not immediately obvious. 

In these complex and compound sentences, the relationship between the two ideas becomes clear. In this example, the two ideas are in contrast to one another.

There are many types of relationships between clauses, but the most common ones are as follows:

This table offers more detail on the types of relationships that exist between clauses in complex sentences.

Type of relationshipSubordinating conjunctionsExamples
Cause-and-effectBecause, since, now that, as, to, soSince you did your chores, you can go play.Now that she feels better, she wants to go back to school.I ordered cake because I know it’s your favorite.
ContrastAlthough, though, even though, whereas, whileIt’s raining in Seattle, whereas it’s sunny in Miami.While they were on vacation, their house sitter stayed with their dog.She drove even though she prefers to fly.
TimeAfter, before, when, while, since, untilAfter they left the movie theater, they walked to a nearby restaurant.Remember to brush your teeth before you go to bed!When I grow up, I want to teach grammar.
Conditionif, unless, only if, whether or not, even if, in case (that)If you like pancakes, you’ll love waffles.He left the light on in case she came home late.Please call me back even if it’s late.

Carefully choosing which type of subordinating conjunction you need is important. After all, these little words can pack a lot of meaning into your sentence. Consider these examples:

The sentences above all use the same independent and dependent clauses, but different subordinating conjunctions. And while the actions remain the same, the relationship between the actions is a little bit different in every example. 

Carefully choosing the correct subordinating conjunction is a simple but powerful way to create rich sentences and convey meaning.

As you can see, learning how to form complex sentences is an excellent way to express more complex ideas. Do you want to know more about cause and effect? Check out this article on Udemy with cause-and-effect examples.

Complex sentences are flexible

Since complex sentences have more than one clause, they give you some flexibility. When you create a sentence with two main ideas, you usually want one of the ideas to stand out more. The other idea is there to support the more important idea. 

When you write a complex sentence, you usually want to place the more important piece of information at the front. For example:

These two sentences contain the same independent clause (it’s time to clean the house) and dependent clause (now that spring is here). However, the first sentence emphasizes that spring is here, while the second sentence places importance on the fact that it’s time to clean the house. 

If you want to learn more about English grammar, check out this article on English grammar 101.

Be careful with that comma!

You might have noticed that in all the examples of complex sentences so far, there is sometimes a comma and sometimes not. It can be difficult to remember whether you need a comma in a complex sentence. Here is an explanation of when you need a comma and when you don’t.

This table offers a quick reference:

Dependent clauseCommaIndependent clause
Independent clauseNo commaDependent clause

Here are some examples:

Commas can be intimidating if you’re not too sure about where they are supposed to go. This guide will help you write complex sentences with more confidence. If you’re interested in learning about tenses in English, check out this article in Udemy.

Complex sentence examples

Now that you know how to recognize complex sentences and how to form them, here is a list of examples of complex sentences. Do you want to challenge yourself? See if you can identify the dependent clause, the independent clause, and the subordinating conjunction in each one. 

  1. He called his mother because he missed her.
  2. Since you’re getting paid today, let’s go out for drinks!
  3. The passenger stepped off the train once it had reached the station.
  4. I would love to travel the world after I finish with school.
  5. If we let them, robots will take over the world.
  6. You have to do your homework whether you like it or not.
  7. While he enjoys skateboarding, surfing is really his favorite.
  8. We’re going to have to walk unless the bus shows up soon.
  9. Now that she has graduated college, she’s going to have to pay her own expenses.
  10. You can call me anytime, even if it’s late.
  11. Financial advisors recommend having some savings in case there’s an emergency.
  12. Even though books are expensive, they’re worth every penny.
  13. Whenever she feels blue, she listens to her favorite song.
  14. People who want to get healthy should walk rather than drive.
  15. Because they’re opportunistic sleepers, dogs take naps whenever they can.
  16. My grandmother used to tell me that if a breeze blew on my face while I crossed my eyes, they would get stuck that way.

Here are some complex sentences from literature:

  1. One cannot think well, love well, sleep well, if one has not dined well. – Virginia Woolf, A Room of One’s Own
  2. We all love to instruct, though we can teach only what is not worth knowing. – Jane Austen, Pride and Prejudice
  3. Prime numbers are what is left when you have taken all the patterns away. – Mark Haddon, The Curious Incident of the Dog in the Nighttime

All these sentences are examples of complex sentences. As you can see, complex sentences are an excellent way to show the relationship between ideas.

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