Time to examine when to use a comma.
The obvious starting point is the coordinate comma. These are very closely related to comma splices because they form a part of the solution to comma splices, so this should be quite easy:).
A coordinate comma is used with a coordinate conjunction in a compound sentence to show where one clause ends and the other begins.
Here are some examples:
- John went running, and he sprained his ankle.
- It began to rain, so they ran inside.
- She had watched the food carefully, yet it had burned at the bottom of the pot.
Tip: Remember the coordinate conjunctions: for, and, nor, but, or, yet, so (FANBOYS for short)
Caution: Sometimes, a sentence comes up that looks like it consists of two main clauses. The sentence really has a compound predicate. A compound predicate consists of two actions performed by the same person or people.
- I turned the corner and ran smack into a patrol car.
To place a comma in front of this coordinate conjunction above would be incorrect because “I” performs the second action as well. That second action is still necessary to complete the full meaning of the sentence. If a comma were to be placed in front of the coordinate conjunction, it would separate essential elements from each other (more about this under Commas and Essential Elements).
Just as using a comma incorrectly can create a comma splice error, so omitting a comma from a compound sentence which requires a comma can create an error called a run-on or fused sentence.
- I don’t eat broccoli and my sister doesn’t eat cauliflower.
This run-on/fused sentence needs some clearer boundaries for its two identifiable compound parts.
- Replace the coordinate conjunction with a period:
I don’t eat broccoli. My sister doesn’t eat cauliflower.
- Replace the coordinate conjunction with a semi-colon:
I don’t eat broccoli; my sister doesn’t eat cauliflower.
- Place a comma in front of the coordinate conjunction:
I don’t eat broccoli, and my sister doesn’t eat cauliflower.
I think most times just using the coordinate comma for the coordinate conjunction would be enough.
Some quick exercise in the next post.