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How to Properly Use Commas and Conjunctions
A compound sentence is comprised of two complete sentences connected by conjunction or set of correlating conjunctions and a comma – usually.
Deciding when and where to use commas is not always intuitive, especially when it comes to some of the more complicated cases when the rules are less clear. For example, the essay writer service states that through learning and comprehending compound sentence rules, you can improve your grammar, whether in a formal letter or just an email.
The Compound Sentence
A compound sentence consists of two independent clauses connected with any coordinating conjunction or a set of correlating conjunctions. Rewind. Let’s throw out some of the grammar-speak and figure out what that sentence means.
An independent clause is essentially a sentence: a subject and verb, usually more (direct objects, indirect objects, adjectives, adverbs, dependent clauses, etc.).
The blue team won the game.
Even though Betty cried last night, she seems fine today.
The preceding three sentences are all independent clauses, the final sentence being an independent clause with a dependent clause tacked on the front (“Even though Betty cried last night,” cannot stand alone as a sentence).
The following words are coordinating conjunctions, which will be used in the center of a compound sentence (usually with a comma) to indicate the transition from one sentence into another.
Susan tried talking to her boyfriend about her bad day, but she needed to talk to her best friend.
My mom went to the store to buy groceries, and on her way home, she stopped at the bank.
You can pick up a cup of coffee for a few dollars, or I can brew a whole pot at home for the same price.
Each of the following examples uses coordinating conjunction between complete sentences.
Sets of Correlating Conjunctions
The following pairs of correlating conjunctions are used together to connect two sentences into a compound sentence, much in the way ordinary conjunction does; only sets of correlating conjunctions rarely need a comma as single correlating conjunction does.
- not only-but also
Either Spot will fetch the stick, or he’ll chase the mailman.
Not only do seniors need to apply for graduation, but they also should plan for their future.
Johnny should both prepare for work, and he should clean the house.
A common error in comma placement in compound sentences is to place the comma after the conjunction. This is incorrect. The comma always belongs before the conjunction in a compound sentence.
Joyce made a pro and con list of her job, and she decided to keep her position.
Joyce made a pro and con list of her job and, she decided to keep her position.
When Not to Use a Comma
Anytime you are not connecting two complete sentences (that is two independent clauses that can stand independently without the rest of the sentence) you should not separate the conjunction with a comma. Read each piece of the sentence (before and after the conjunction) to determine whether each clause is indeed independent. Similarly, the same rules apply for correlating conjunctions.
Jessie decided to make her bed before she left for school, and she was proud of herself.
Either John ate the cookies, or Philip ate them.
Jessie decided to make her bed before she left for school, and was proud of herself.
Either John or Philip at the cookies.
Both of the incorrect examples above do not have a second subject and cannot stand independently as a sentence: “Was proud of herself.” or “John.”
Also, American and British grammar are moving toward less sentence punctuation (especially in casual, journalism, and essay writing) for easier reading. For short compound sentences that cannot be misunderstood, omitting the comma is okay. This is especially true in cases where the first clause of the compound sentence is short.
Jamal threw a snowball at me but I ducked in time.
Jonah gathered his books but the bus had already left by the time he reached the bus stop.
Jamal threw a snowball at me from the fort in the front of the yard but I ducked in time.
The first part of the above compound sentence does not reach the conjunction until almost the end of the sentence, so a comma should be used before but.
Use your judgment when writing compound sentences, and if in doubt of whether a sentence should include a comma with the conjunction, including the comma. A true compound sentence could rarely be considered incorrect with a comma before the conjunction.