A comma is a punctuation mark that serves many purposes. The rules for using commas to separate list items and numbers tend to be straightforward, but the guidelines for using commas to indicate divisions in sentences that result from phrases, clauses, and conjunctions can be a bit more difficult to master.
We’ve put together a guide to help you determine whether you should or should not use a comma when the words “as” and “since” are used in the middle of your sentences. Read on to learn more!
When Should “As” be Preceded by a Comma?
When coordinating conjunctions (“for,” “and,” “nor,” “but,” “or,” “yet,” and sometimes “so”) fall in the middle of a sentence, they are typically preceded by a comma (e.g., when connecting independent clauses).
Commas need to be used correctly, but there are a lot of rules to remember.|
Using commas can be difficult as there are so many rules.
However, when it comes to writing, not all rules are steadfast because ensuring clarity is a priority. Consider the following:
The students completed the assignment as their teacher instructed them to.
The students completed the assignment, as their teacher instructed them to.
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In the first sentence, the students completed the assignment in the way they were instructed to, and in the second sentence, they completed the assignment because they were instructed to. Therefore, a comma before a subordinating conjunction may be necessary to ensure clarity.
When Should “Since” be Preceded by a Comma?
Similarly, when “since” is used as a subordinating conjunction meaning “because” or referring to something that happened after a point in time, it is not typically preceded by a comma:
Using commas can be difficult since there are so many rules.
My grades have improved since learning how to use commas.
However, a comma is needed before “since” when the preceding clause contains a negative verb:
The teacher couldn’t understand my report, since it wasn’t properly punctuated.
Proofreading & Editing Services
Hopefully, this improves your understanding of when “as” and “since” need to be preceded by a comma. Even once you’re confident in your punctuation skills, using a professional proofreading and editing service is a great way to ensure your writing is clear and error-free. We have hundreds of expert editors who are ready to help, and you can submit a free trial document to learn more!