Commas
Commas
Commas Are Used in Many Ways
Whereas most of the punctuation we've looked at is used in just one or two ways, commas can show up for a greater variety of purposes, making it a bit tougher to test whether a comma is appropriate. But we do have a few rules about when you definitely should NOT use a comma, so it's better to start there, to see if you can eliminate any answer choices with commas for one of these reasons.
Never Use a Comma Between a Title/Label and a Proper Noun
Whenever you see a proper noun (like the name of a person) with a label or title before it, you should never use a comma between the label and the proper noun. For example, we might say "The theory of evolution was first proposed by scientist Charles Darwin" or "The Harry Potter series was written by author J.K. Rowling". In these cases, the labels or titles are "scientist" and "author", so we don't place a comma after them. It would be incorrect to say "The theory of evolution was first proposed by scientist, Charles Darwin". We could even be more loose with what we consider a label/title, for example, we could say "The series was devoured by book enthusiast Dave" - here the label is "book enthusiast", so we don't want a comma between "book enthusiast" and "Dave". This also applies to more official titles like "President" or "Doctor", although it tends to be more obvious that you don't want a comma there. On the SAT, if you see a comma coming between a label or title and a proper noun, you can eliminate it.
*An exception to this is when the label is preceded by the word "a" or "an". For example, "It was a scientist, Charles Darwin, who proposed the theory of evolution" is ok. But I wouldn't worry about this exception because I've never seen it come up on the SAT.
Never Separate a Subject and its Verb with a Single Comma
Whenever you have a noun and a verb that is performed by that noun, they should not be separated by a comma. For example, "I went to the store" is correct, but "I went, to the store" is incorrect. This might seem obvious in this simplified example, but the SAT will have more complex sentences where it might not be so obvious. Note that we said a "single comma"; this is because you might have a nonessential clause (also known as a parenthetical element) coming between a noun and it's verb, and that is ok. For example, "John, who needed several things, went to the store" is correct. So when you see a comma in an answer choice, check whether it comes between a noun and the verb that is performed by that noun, without being part of a pair of commas that separate a nonessential clause. If it does come between a noun and its verb, you can eliminate it.
Don't Put a Comma Before Essential Clauses
Essential clauses are dependent clauses that are essential to the meaning of the sentence. They often help to specify which nouns or pronouns we are talking about. We might be able to remove them without making the sentence grammatically incorrect, but the sentence wouldn't retain the same meaning. For example, in the sentence "The t-shirts that are marked with red tags are 50% off", the essential clause is "that are marked with red tags". This specifies which t-shirts are on sale and is essential to the meaning of the sentence. If we omit it ("The t-shirts are 50% off"), the sentence is still grammatically correct, but it doesn't convey the same meaning because it now sounds like all the t-shirts are on sale. Here is another example: "The students who study hard will do well on the test." In this sentence, the essential clause is "who study hard". If we omit it ("The students will do well on the test"), the sentence is still grammatically correct, but it doesn't convey the same meaning because it now sounds like all the students will do well on the test.
"That" is used to start essential clauses and should not be preceded by a comma.
The word "that" is used to specify which noun or pronoun we are talking about. Clauses that start with "that" are essential to the meaning of the sentence, so they should not have a comma before them. If you see an answer choice with a comma before the word "that", you can eliminate it.
"Which" is used to start non-essential clauses and can be preceded by a comma.
The word "which", while often used similarly to "that", is used to start non-essential clauses. These clauses can be separated by a comma. Take the following example: "The blue t-shirt, which I really like, is on sale." In this case, the clause "which I really like" is non-essential. The sentence doesn't really change its meaning if we omit it ("The blue t-shirt is on sale"). It's still clear what shirt we're talking about; we just lose the additional information that I really like the shirt, so we can separate it with commas.
Some pronouns can be used in both essential and non-essential clauses.
Some pronouns, like "who", can lead off both essential and non-essential clauses. For example, in the sentence "The man who is wearing the red shirt is my friend", the phrase "who is wearing the red shirt" is essential to the meaning of the sentence, so we don't to separate it with commas. But if we were to say "I'm friends with Steve, who is a nice guy", the phrase "who is a nice guy" is non-essential, so we can separate it with a comma. It's adding extra information about Steve, but it's not necessary to know who we're talking about.
Do Use a Comma to Separate Non-Essential Information
While there are many reasons for using commas, when an SAT answer choice ends up being right because of a comma, it is almost always because the comma is used to separate a non-essential clause, clauses that add extra information but are not essential to the meaning of the sentence.
Non-essential clauses can show up at the beginning, middle, or end of a sentence.
These "extra information" clauses can show up at the beginning of a sentence, in the middle of a sentence, or at the end of a sentence.
Here are some examples:
- Hoping to find a good deal, Devin went to the store.
- Devin, who loves a good deal, went to the clearance sale.
- Devin went to the store, hoping to find a good deal.
When in Doubt, Leave the Comma Out
When it comes down to answer choices where the only difference is the presence or absence of a comma, most of the time the correct answer will be the one without the comma. Check to see if the comma seems to be separating a non-essential clause. If not, choose the option without the comma, unless you see another obvious reason why the comma should be there.