Why Are Complex Sentences and Commas Important?
Whether you are in high school, college, graduate school, or just writing for yourself, commas tend to give all of us difficulty at times. Most of the old clichés don’t work either. For example: “When in doubt, leave it out.” Are we to eliminate commas whenever we have doubts? Or, should we place a comma whenever we think we should pause? Well, pauses can be rather subjective. So it looks as though we need to buckle down and seriously examine the structure of each kind of sentence and the punctuation rules that go with each type.
Simple sentences contain only one complete thought—one independent clause. A clause is a group of words that has a subject and a verb. An independent clause can stand alone and is not dependent on any other word group to make sense.
Here are the three main types of compound sentences:
- Compound sentences that have two independent clauses separated with a FANBOYS conjunction (for, and, nor, but, or yet, so) and a comma in front of the conjunction.
- Compound sentences that have two independent clauses separated with a semi-colon (No conjunction. Just a semi-colon.)
- Compound sentences that have independent clauses separated by a transition. In this case, a semi-colon should be placed just before the transition and a comma goes after the transition.
Examples of Simple Sentences
- John is my brother. (Simple sentence with one subject.)
- Mary and her sister have similar features. (Simple sentence with two subjects.)
- John went to the store and bought milk and eggs. (Simple sentence with two verbs.)
Examples of Compound Sentences
- Sarah went to the mall, and she shopped all afternoon. (FANBOYS conjunction)
- Sarah went to the mall; she shopped all afternoon. (semi-colon, no conjunction)
- Sarah went to the mall; moreover, she shopped all afternoon. (transition)
Tip: It’s a good idea to review compound sentences and practice writing and punctuating each kind before moving to complex sentences. If you have reviewed compound sentences, you are less likely to become confused as we delve into complex sentences.
A complex sentence has at least one independent clause and one or more dependent clauses. A dependent clause depends on the rest of the sentence for its meaning. It is not a complete thought by itself. Example: When the sun came out (dependent clause).
1. Subordinating Conjunctions
These introduce one kind of dependent clause.
Examples of Common Subordinating Conjunctions
in order that
Additional subordinating conjunctions can be found at the Capital Community College’s website, Guide to Grammar and Writing, or here. Most English/grammar textbooks have a list of subordinating conjunctions with page numbers in the index at the back of the textbook.
Note: The prefix sub- means under. Usually, writers put less important information into a dependent clause. The more important information goes in the independent clause. Keep that idea in mind when writing complex sentences because you want your readers to pay closer attention to your more important ideas. Don’t tuck your important information into a dependent clause. Since a comma rule is associated with these conjunctions, you need to memorize them so that you can readily recognize them when they appear in a sentence.
1. At the End of a Dependent Clause
When the subordinating conjunction introduces a dependent clause that comes at the beginning of the sentence, or before the dependent clause, put the comma at the end of the dependent clause. Where does the dependent clause end? It ends where the main subject and verb begin.
Example: When the rain stopped, the sun peeked out from behind the clouds.
The main subject and verb are "sun" and "peeked," so the comma is placed at the end of the dependent clause, after the word "stopped."
2. Never Use a Comma When "That" Introduces a Dependent Clause
The word "that" can refer to people or objects. In writing, select the word "that" when your dependent clause is necessary to the meaning of the sentence.
Example 1: Jonathan knew that the girl in the red dress was his long-lost cousin.
The dependent clause (that the girl in the red dress) is necessary for the meaning of the sentence. If you took out the dependent clause, the meaning of the sentence would be changed.
Example 2: My mother told me that the white house on the corner belonged to my uncle.
The dependent clause (the white house on the corner) is necessary for the meaning of the sentence.
Tip: Use the word "that" to introduce dependent clauses that are essential for the meaning of the sentence. Never use commas with dependent clauses beginning with "that."
3. Around Dependent Clauses Beginning With the Word "Which"
These dependent clauses always take commas because they are NOT essential for the meaning of the sentence. In other words, if you remove the dependent clause, you will not change the meaning of the sentence. These dependent clauses add good information to the sentence, but the actual meaning of the sentence is not changed by this dependent clause.
Example 1: Susan placed the stack of books, which were unbearably heavy, on the table by the door.
The dependent clause (which were unbearably heavy) adds good information to the sentence, but removing the clause does not change the meaning of the sentence: Susan placed the books on the table by the door.
Example 2: The blue purse, which I really don’t need, is quite heavy.
The dependent clause (which I really don’t need) is not essential for the meaning of the sentence. The meaning of the sentence: The blue purse is quite heavy.
Example 3: The painting, which he admired, was moved into the living room.
"Which he admired" is not essential for the meaning of the sentence.
Removing the dependent clause does not change that meaning; therefore, the dependent clause is not essential for the meaning of the sentence. Commas go around the dependent clause.
Remember: The word "which" refers to things/objects, not people. Use "which" to introduce dependent clauses that are NOT essential for the meaning of the sentence. Always use commas with "which" clauses.
4. Who and Whom Clauses
Dependent clauses beginning with "who" or "whom" take commas depending on whether the clause is necessary/essential for the meaning of the sentence. If the clause is necessary for the meaning of the sentence, do NOT use commas. If the clause is NOT necessary for the meaning of the sentence, DO use commas.
Example 1: The girl who stood by the door for over an hour is my sister.
The dependent clause (who stood by the door for over an hour) is essential for the meaning of the sentence. It’s not just any girl — it’s the one who stood by the door for over an hour. In this case, do NOT use commas.
Example 2: The puppy who has slept all day is mine.
"Who has slept all day" is essential for the meaning of the sentence. NO commas.
Example 3: The sad-looking boy, whom I respect, made the honor roll this semester.
"Whom I respect" is not essential for the meaning of the sentence. DO use commas.
Academic vs. Popular Writing
This article primarily targets academic writing, but you can’t go wrong with following these suggestions for any genre of writing. Do notice, however, that popular writing often breaks some academic grammar rules. Occasionally, when your audience is non-academic readers, it is more effective if you don’t adhere too strictly to the “rules.” For example, in an academic paper, fragments can cause your grade of A to plunge drastically because fragments are considered a huge mistake in the classroom. However, with fiction, creative non-fiction, or journalism, fragments can actually be quite effective. Please realize that the rules differ sometimes, and remember that the academic rules are a guideline—not set in stone. But no matter the form of writing, the goal is still to be clear, concise, and effective.
Summary and Suggestions
Practice and more practice! The best practice is to write your own simple, compound, and complex sentences. When you write sentences and place the commas, ask someone who is familiar with these rules to check your work. Another option is to take online quizzes that give you immediate feedback. Many of these sites provide brief explanations with examples of each sentence. The quizzes follow the explanations, and you can find out what you missed immediately. I have used both of the websites below in my classroom.
Research Basis for Writing Effective Sentences
You may notice that I advocate practicing writing these different types of complex sentences. The online grammar quizzes are great, but nothing can replace actual writing. Research supports that practicing writing not only improves your writing; it also improves reading.
By the time I selected a topic for my dissertation, I knew I wanted to research reading-writing connections. Research consistently supports the idea that students whose teachers teach these two subjects together usually score higher in both subjects than students who learn these subjects separately. Effective writing is essential for lifelong success.
Another research-based strategy that has proven valid is the idea that grammar is best learned in the context of the students’ own writing. A comprehensive report on reading-writing research published by the Carnegie Foundation, Writing to Read: Evidence for How Writing Can Improve Reading (2010), provides information on numerous studies that support the importance of students’ learning to write effectively. This report can be accessed here:
You can locate additional reading-writing research in my 2008 Auburn University dissertation, The Effects of Teaching Critical Thinking and Reading Comprehension Strategies on the Writing of Developmental English Students in a Community College.
Sunday sivile on September 13, 2018:
Sunday went to hospital because she was sick
Nancy McLendon Scott (author) from Georgia on April 19, 2014:
Thank you! Any suggestions you have are appreciated.
The Examiner-1 on April 19, 2014:
Hello simondixie, again this is a very useful Hub but maybe a lot to take in at one sitting. I may read it again. I may also be doing thse things and not know what they are called.I gave this a thumbs up and more, plus I shared and pinned it.
Nancy McLendon Scott (author) from Georgia on April 19, 2014:
Firoz from India on April 19, 2014:
Great Suggestions. Good work.