Complex and Compound Sentences: Examples & Rules

  in Research   Posted on January 11, 2021

English composition requires a fundamental grasp of the English language. Among the basic concepts needed to improve writing in English is knowledge of sentence structure. However, with the many nuances in the language, mastering this can prove to be quite challenging for native and foreign speakers alike.

This article aims to help readers further polish their writing skills by explaining the construction of complex sentences in detail. More specifically, this article will focus on the definition and structure of complex sentences. In addition, this will illustrate a number of complex sentence examples and discuss various common mistakes to avoid when writing.

After reading this article, the reader should be able to identify and distinguish a complex sentence from other sentence types. They should be able to construct complex sentences on their own.

complex sentence

Table of Contents

  1. What Is a Complex Sentence?
  2. Common Structure and Examples of Complex Sentences
  3. When To Use Complex Sentences
  4. Common Complex Sentence Mistakes and How To Avoid Them

English is alternately simple and complex for non-native speakers. Depending on which language one compares it to, writing in English may be easier or more difficult. For starters, English is not a tonal language, which uses pitch to distinguish word meaning. Pitch when applied to English is used to emphasize emotion (Shoebottom, 2018).

Apart from the tonal implications, English sentences also differ in structure from over half the world’s languages. Sentences traditionally contain a subject, a verb, and an object. Typically, the order is Subject-Verb-Object, where the subject performs the action (verb) to the object. Babbel Magazine notes that 41% of languages use the S-V-O pattern when creating sentences. However, an even bigger number of languages (47.5%) commonly use the Subject-Object-Verb syntax (S-O-V) instead (Devlin, 2018). For non-native English speakers more inclined to use S-O-V, this may take some time getting used to.

Source: Languages of the World

Writers expecting to step out of their native language need to understand all cultural, grammatical, and ways of speaking, specificities. (Alix-Gravellier, 2020). Among the unique features of writing in English are sentence structures. They range from the simple to the complex, which are differentiated by the type and number of clauses used.

What Is A Complex Sentence?

Complex sentences contain one main (independent) clause and at least one dependent (subordinate) clause. A complex sentence is different from the other types as it requires both kinds of clauses. As complex sentences have a main clause and subordinate clause, it follows that the clauses are unequal. A coordinating conjunction is required to ensure that the inequality between these clauses stays. Common coordinating conjunctions include if, when, since, because, while, and after.

  • Example: He ate my food while I was sleeping. 

Types of Clauses

Clauses come in two types: Independent and Dependent. Also known as the main clause, an independent clause contains both a subject and a predicate and is considered a sentence on its own. In addition, an independent clause is finite, which means it contains a verb that denotes tense. In the complex sentence example above, the clause “He ate my food” is the main clause.

Also known as a subordinate clause, a dependent clause is a group of words that does not convey a complete thought or idea. It needs a main clause for it to be considered as a complete sentence. While they can be finite, dependent clauses do not require a tense, as it gets its time reference from the main clause. Dependent clauses usually start with a subordinator word such as “when,” “if” or “which.” Similarly, in the complex sentence above, the subordinate clause was “while I was sleeping.” 

Other Sentence Types

Complex sentences are only one of the many types of sentences based on structure. Depending on whether they carry the main clause and/or subordinate clauses, sentences can be classified into the following types other than complex: simple, compound, and compound complex. For better appreciation, the examples used below are offshoots of the clause examples above.

  • Simple – Simple sentences contain a single independent clause consisting of a subject and predicate.
    • Example: He ate my food. 
  • Compound – Compound sentences contain at least two independent clauses and use a conjunction such as and, or, with, etc, to connect them.
    • Example: I wasn’t hungry during lunch, so he ate my food. 
  • Compound complex – A compound complex sentence contain at least two independent clauses and at least one subordinate clause.
    • Example: He ate my food while I was sleeping, but he never apologized.

Common Structures and Examples of Complex Sentences

Apart from the presence of both independent and dependent clauses, the use of the coordinating conjunction connects the clauses but displays a complex relationship between the two; indicating which is dominant and which is subordinate. The structure is usually an independent clause + subordinating conjunction + dependent clause.

  • Example: Ask your instructor if you don’t understand the instructions. 

If the order is reversed and the dependent clause is placed first, the subordinating conjunction may be placed in front. The structure becomes subordinating conjunction + dependent clause + independent clause.

  • Example: If you don’t understand the instructions, ask your instructor. 

Complex sentence structures

When To Use Complex Sentences

Complex sentences help connect one idea with another by showing relationships between clauses (Powers, 2015). Combining clauses into one sentence strengthens the whole idea, which either an independent or dependent clause is unable to do. Among the instances you should use complex sentences include:

  1. When you want to show relationships such as cause-and-effect, contrast, and time.
    • Example: If you commit the crime, you must do the time. 
  2. When you want to illustrate the complicated thinking required to understand logical concepts. They can also replicate the patterns of thinking of a deep thinker.
    • Example: If you love someone, set them free.
  3. When you want the reader to focus on the clause with more weight rather than another part of a sentence.
    • Example: The law may be harsh, but it is the law.
  4. When you want to combine smaller sentences and turn them into longer but more melodic sentences.
    • Example: As I walked through the valley of the shadow of death, I took a look at my life, and realized there is none left.
  5. When you want to create cumulative sentences patterned after the way people speak.
    • Example: Many years later, as he faced the firing squad, Colonel Aurelian Buendia was to remember that distant afternoon when his father took him to discover ice.

Common Complex Sentence Mistakes and How To Avoid Them

Compared to other sentence types, complex sentences are less error-prone as the clauses have an established relationship. Below are two of the most common errors that occur when writing complex sentences.

Dangling Modifiers

Complex sentences, when not done properly, can lead to some confusing prose (The Writing Lab, 2020). This is more evident with the presence of dangling modifiers.

A dangling modifier occurs when a modifier is placed in such a way that it could be misattributed to a word other than its intended object. This leaves the modifier hanging or “dangling.”

Example: the sentence “After taking a bath, the towel needs drying.” needs modification, as the subject who took a bath isn’t really the towel. A better complex sentence would be, “I need to dry the towel after taking a bath.”

Sentence Sprawl

Sentence sprawl occurs when too many equally weighted phrases and clauses are placed in a single sentence, which produces tiresome sentences. Usually, it happens when many subordinate or coordinate clauses are placed together in one sentence (Rivas, 2020).

Example: Break the glass in case of emergency, which when unaddressed, can cause great damage, and might lead to casualties. While technically the sentence is acceptable, there are far too many subordinate clauses that crowd the main clause.

Complex Sentences Should Not Be Complicated

Once the definition, rules, and syntax are established, writing complex sentences should be easy. Like everything else, it takes practice and attention to learn a valuable skill. English composition is no exception and continuous practice and an enthusiasm to learn the nuances of the language will boost communication abilities. English has many peculiarities that confuse even the most native of speakers, and mastering these rules may take some time.

Poorly written or error-riddled sentences can distract readers enough to overlook the message or stop them from reading further. As rudimentary communication skills are a requirement in almost all professional jobs, competent writing can spell the difference between a rank-and-file position to getting a promotion (Birkett, 2019).

This article does not cover the entire spectrum of complex sentences but rather serves as an introductory guide. There are even more complex nuances involving clause types and sentence subtypes that will require further studies. Be reminded though, that language and grammar are continually evolving and may change over time.



  1. Birkett, A. (2019, December 09). Are grammar mistakes costing you money?
  2. Devlin, T. M. (2018, July 13). How to use sentence structure to learn a foreign language.
  3. Pereseltvaig, A. (2011, December 19). On statistical universals. Languages of the World.
  4. Powers, K. (2015, July 01). Why use complex sentences? English Writing Teacher.
  5. Rivas, M. (2020). The Grammar Guru: Sentence sprawl. UNL Newsroom.
  6. Shoebottom, P. (2018). The English language. ESL Frankfurt International School.
  7. The Writing Lab. (2020). Dangling modifiers and how to correct them. OWL Purdue University.