Complex and Compound Sentences: Examples & Rules for 2025

by Imed Bouchrika, Phd

Co-Founder and Chief Data Scientist

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Proper English composition is important regardless if you are earning an English degree or not. However, it requires a solid understanding of the English language, including basic concepts like sentence structure.  This can be hard to do considering the many nuances in the language. As such, mastering proper sentence structure and composition can prove challenging for native and foreign speakers alike.

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

After reading this guide, 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 and Compound Sentences Table of Contents

1. What Is a Complex Sentence?
2. Common Structure and Examples of Complex Sentences
3. When To Use Complex Sentences
4. How Do Complex Sentences Impact Communication in Professional Settings?
5. Common Complex Sentence Mistakes and How To Avoid Them
6. How to Combine Simple Sentences into Effective Complex Sentences
7. What Role Does Short-Term Online Education Play in Enhancing Sentence Complexity?
8. How Does Formal Education Influence Advanced Sentence Construction?
9. How Can Additional Educational Resources Enhance Your Sentence Construction Skills?
10. Can Accelerated Learning Pathways Enhance Your Sentence Mastery?
11. What Role Do Accredited Online Programs Play in Enhancing Sentence Construction?
12. How Can Professional Peer Feedback Enhance Sentence Construction?

Mastery of proper English grammar is an important tool in every student’s arsenal. Whether you are drafting a book report or writing a research proposal, understanding the ins and outs of the English language is critical. However, 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.

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 compound sentence 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. 
• 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. 
• 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.
• 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. 

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. Example: If you commit the crime, you must do the time. 
3. 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.
4. Example: If you love someone, set them free.
5. 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.
6. Example: The law may be harsh, but it is the law.
7. 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.
8. 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.
9. 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.
10. 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.

How Do Complex Sentences Impact Communication in Professional Settings?

Complex sentences enhance professional communication by effectively linking related ideas and providing necessary context that simple sentences alone cannot convey. Their strategic use of dependent clauses creates a logical flow, emphasizing conditions, causes, and relations without interrupting clarity. This refined structure not only improves readability but also reinforces the writer’s credibility and authority. Professionals aiming to elevate their communication skills may benefit from targeted training and advanced programs, such as BCBA certification online, to master the nuances of complex sentence construction in diverse professional contexts.

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.

How to Combine Simple Sentences into Effective Complex Sentences

Combining simple sentences into complex sentences is essential for improving writing sophistication and clarity. Complex sentences allow you to connect ideas, convey relationships, and make writing more engaging. Here's how to turn simple sentences into effective, complex sentences:

• Use Subordinating Conjunctions: Combine simple sentences using subordinating conjunctions like "because," "although," or "if." For example, "She was tired." and "She finished the project." become "Although she was tired, she finished the project." This structure shows how ideas relate (e.g., contrast, cause, effect) and avoid choppy writing.
• Incorporate Relative Pronouns: Relative pronouns like "who," "which," or "that" add detail to the sentence. For example, "I met a writer." and "She was very inspiring." combine into "I met a writer who was very inspiring." This structure lets you add information without breaking the flow of the sentence.
• Use Conditional Clauses: If expressing a condition or hypothetical scenario, use "if" clauses. For example, "She will attend the meeting." and "She has to finish the report first." becomes "She will attend the meeting if she finishes the report first." Conditional clauses show cause-and-effect relationships, adding depth to your writing.
• Establish Time or Cause-and-Effect Relationships: Show how actions are connected in time or by cause and effect. "I started running." and "I lost weight." combined into "I started running because I wanted to lose weight." This structure makes the sequence or reason behind actions clear.
• Use Appositives for Additional Information: Appositives provide extra details about nouns. For example, "Sarah is an excellent student." and "She works hard every day." become "Sarah, an excellent student, works hard every day." Appositives streamline sentences while adding clarification or emphasis.

Complex Sentences Should Not Be Complicated

Once the definition, rules of complex sentences, 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 complex sentence 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. You can peruse these free resources for English students should you want to explore this topic further. Be reminded though, that language and grammar are continually evolving and may change over time.

What Role Does Short-Term Online Education Play in Enhancing Sentence Complexity?

Short-term online education initiatives deliver targeted, intensive modules that focus on advanced writing techniques and complex sentence construction. These programs enable practitioners to quickly assimilate practical strategies for structuring and refining sentences while addressing immediate communication challenges. By emphasizing timely feedback and streamlined content delivery, learners can integrate nuanced grammatical rules into their writing toolkit in a condensed timeframe. Many professionals leverage such accelerated approaches to complement formal education, optimizing their skill set without lengthy academic commitments. For additional details on this pathway, consider exploring what degree can I get online in 6 months.

How Does Formal Education Influence Advanced Sentence Construction?

Formal education cultivates a deep understanding of linguistic principles and advanced writing techniques that extend beyond basic grammar rules. Academic programs provide structured exposure to varied sentence constructions, encouraging critical analysis of language usage and stylistic nuances. This systematic training enables learners to dissect the roles of independent and dependent clauses and to experiment with diverse sentence structures in a controlled environment. Such academic rigor is often featured in programs like a bachelor's degree or associate's degree, where curriculum design emphasizes methodical revision practices and iterative improvement. By engaging in formal coursework, students refine both their technical skills and their ability to articulate complex ideas clearly and succinctly.

How Can Additional Educational Resources Enhance Your Sentence Construction Skills?

Advancing writing proficiency often requires structured educational programs beyond self-study. Engaging in advanced writing courses can offer targeted strategies for refining syntactical structures and exploring diverse clause arrangements. These courses emphasize practical exercises and detailed feedback to build accuracy in sentence construction while fostering a deeper understanding of nuance in written communication. For those seeking flexible learning options, consider exploring open enrollment colleges that provide comprehensive programs designed to enhance professional writing development.

Can Accelerated Learning Pathways Enhance Your Sentence Mastery?

Accelerated learning programs offer a time-efficient approach to mastering complex sentence construction by integrating intensive coursework with practical exercises. These programs are designed to rapidly advance students from foundational grammar to nuanced writing techniques through structured, focused modules and immediate, expert feedback. This method supports a balanced development of both technical proficiency and stylistic finesse, enabling learners to overcome persistent grammatical challenges. For professionals or students aiming to fast-track their education, exploring the quickest associates degree can provide a strategic advantage in achieving advanced writing skills while accommodating a busy schedule.

What Role Do Accredited Online Programs Play in Enhancing Sentence Construction?

Accredited online programs offer a structured curriculum that integrates advanced writing strategies with practical exercises designed to hone sentence construction skills. These programs emphasize critical analysis, iterative practice, and timely feedback, enabling learners to refine their technical proficiency and stylistic precision. They also promote self-paced learning that complements professional development needs. For further information on recognized institutions in this domain, consider reviewing our article What are the best online universities?

How Can Professional Peer Feedback Enhance Sentence Construction?

Engaging in structured peer review and professional editing offers targeted insights that refine sentence construction by revealing subtle inconsistencies and overlooked errors. Experienced advisors help pinpoint areas where clauses can be streamlined or clarified, ensuring that complex ideas are communicated with precision. Furthermore, incorporating external feedback promotes a dynamic learning environment where writers can iteratively improve stylistic and syntactic finesse. For those seeking academic insights into advanced educational pathways, consider exploring our guide What is the easiest master's degree to get?

Key Insights

• Understanding Sentence Structure: Mastering English composition involves grasping basic concepts like sentence structure, which can be challenging due to the language's nuances.
• Complex Sentences Defined: Complex sentences contain one main (independent) clause and at least one dependent (subordinate) clause, linked by subordinating conjunctions like "if," "when," and "because."
• Types of Clauses: Independent clauses can stand alone as sentences, while dependent clauses cannot. Complex sentences combine these to convey detailed ideas.
• Other Sentence Types: Simple sentences have one independent clause, compound sentences have two or more independent clauses, and compound-complex sentences have multiple independent clauses plus at least one dependent clause.
• Usage of Complex Sentences: Use complex sentences to show relationships between ideas, illustrate complex thoughts, emphasize certain parts of a sentence, combine shorter sentences, and mimic natural speech patterns.
• Common Mistakes: Avoid dangling modifiers, which misplace modifying phrases, and sentence sprawl, which overloads sentences with too many clauses, making them cumbersome.

FAQ

1. What is a complex sentence? A complex sentence is a type of sentence that includes one main (independent) clause and at least one dependent (subordinate) clause, connected by subordinating conjunctions like "if," "when," or "because."
2. How do complex sentences differ from other types of sentences? Complex sentences differ in that they contain both an independent clause and a dependent clause. In contrast, simple sentences have only one independent clause, compound sentences have two or more independent clauses, and compound-complex sentences have multiple independent clauses and at least one dependent clause.
3. Why should I use complex sentences in my writing? Complex sentences help you connect ideas and show relationships like cause and effect or contrast. They allow for more nuanced and detailed expression, making your writing more engaging and reflective of deeper thinking.
4. What are common errors to avoid when writing complex sentences? Two common errors are dangling modifiers, where a modifier is incorrectly placed and misattributes meaning, and sentence sprawl, where too many clauses are packed into one sentence, making it cumbersome and difficult to read.
5. How can I identify a dependent clause in a sentence? A dependent clause, also known as a subordinate clause, does not convey a complete thought and cannot stand alone as a sentence. It often begins with subordinating conjunctions like "when," "if," or "which."
6. Can you provide an example of a complex sentence? Certainly! An example of a complex sentence is: "While I was sleeping, he ate my food." Here, "While I was sleeping" is the dependent clause, and "he ate my food" is the independent clause.
7. What is a dangling modifier, and how can I fix it? A dangling modifier is a word or phrase that modifies a word not clearly stated in the sentence, leading to confusion. For example, "After taking a bath, the towel needs drying" should be corrected to "I need to dry the towel after taking a bath."
8. What is sentence sprawl, and how can it be avoided? Sentence sprawl occurs when a sentence includes too many clauses of equal importance, making it lengthy and tiresome. To avoid this, break up the sentence into smaller parts or prioritize and simplify the information.
9. Are there resources to further improve my understanding of complex sentences? Yes, numerous free resources are available for English students. These can provide more in-depth exploration of clause types and sentence subtypes, helping you refine your writing skills further.

References:

1. Birkett, A. (2019, December 09). Are grammar mistakes costing you money? CXL.com.
2. Devlin, T. M. (2018, July 13). How to use sentence structure to learn a foreign language. Babbel.com.
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.