10 Comma Cases In Which More Is More

The movement toward open punctuation — the omission of commas in cases in which they are deemed optional — has its merits, but writers and editors should take care to retain commas — or even insert additional ones — to clarify meaning:

1. "He points to the benefits and wonders how schools can justify not investing in tools for disabled students."
Because wonders can be a noun as well as a verb, and because a pairing of the noun form with benefits initially makes sense, it might be misread here as such. To avoid this misunderstanding, insert a comma after benefits to give the reader pause and signal a new thought: "He points to the benefits, and wonders how schools can justify not investing in tools for disabled students." Alternatively, alter the introductory phrase and make the following phrase an independent clause: "Pointing to the benefits, he wonders how schools can justify not investing in tools for disabled students."

2. "The dog should be content to bark at passing trains and slumber."
The sentence incorrectly implies that the dog barks at two things: passing trains and slumber. But bark at refers only to trains, not to slumber. How about reordering the sentence to place slumber first? ("The dog should be content to slumber and bark at passing trains.") Now he's slumbering at passing trains, then barking at them. Either introduce a comma or insert a parallel-signaling to, or both: "The dog should be content to bark at passing trains, and to slumber."

3. "Couch or calisthenics? A majority of California students are opting for a couch based on the results of the state's annual physical fitness test."
As the second sentence is structured, the couch appears to be based on the fitness test results. Insert a comma after couch to clarify the structure (and in the initial sentence, follow couch with a comma there, too, for the same reason): "Couch, or calisthenics? A majority of California students are opting for a couch, based on the results of the state's annual physical fitness test." Better yet, invert the syntax in the second sentence: "Couch, or calisthenics? Based on the results of the state's annual physical fitness test, a majority of California students are opting for a couch."

4. "The world contains too many bored fourteen-year-old boys and ex-boyfriends bearing grudges."
This reference to a particular woman's two greatest classes of nemeses is taken out of context, but it still should be clear that only those in the latter category bear grudges. Therefore, a comma should separate the two categories: "The world contains too many bored fourteen-year-old boys, and ex-boyfriends bearing grudges." Or, if the context allows, reverse the order and strengthen the parallel structure: "The world contains too many ex-boyfriends bearing grudges, and too many bored fourteen-year-old boys."

5. "Halle Berry is the first African American woman to win a Best Actress Oscar for her performance in Monster's Ball."
As punctuated, this sentence implies that more than one African American actress was in contention for an Academy Award for Berry's performance. To set the record straight, set the qualification off with a comma: "Halle Berry is the first African American woman to win a Best Actress Oscar, for her performance in Monster's Ball." Here's a smoother revision: "Halle Berry, who won a Best Actress Oscar for her performance in Monster's Ball, is the first African-American woman to take home the award."

6. "The prison plays an important role during the film's third act, in which our hero is arrested thanks to the villain's devious machinations."
The tag phrase "thanks to the villain's devious machinations" should be set off from the rest of the sentence with a comma. Better yet, insert that parenthetical phrase into the middle of the sentence so that the result of the plotting dramatically punctuates the sentence: "The prison plays an important role, during which, thanks to the villain's devious machinations, our hero is arrested."

7. "Americans divide Russians into authoritarians and democrats with no regard for native context."
The sentence mistakenly implies that the two categories in question are "authoritarians" and "democrats with no regard for native context. The writer meant, "With no regard for native context, Americans divide Russians into authoritarians and democrats." (Or start that sentence with Americans, followed by a comma.) Those revisions are more elegant than the simplest solution, employed above in other examples: "Americans divide Russians into authoritarians and democrats, with no regard for native context."

8. "Another astronomer named Edwin Hubble cast his eye on the pulsing light of distant variable stars called Cepheids."
The initial phrase of this sentence implies the previous mention of another astronomer by that name. Solve this error by setting the name apart as an appositive, with framing commas (and delete the extraneous named): "Another astronomer, Edwin Hubble, cast his eye on the pulsing light of distant variable stars called Cepheids."

9. "High school students who carry a poor or no understanding of evolution into college are less likely to pick careers in the biological and geological sciences."
"Or no" is a parenthetical phrase in which no parallels poor as an option, and it could be omitted with no structural damage to the sentence, so it should be enclosed by a pair of commas: "High school students who carry a poor, or no, understanding of evolution into college are less likely to pick careers in the biological and geological sciences."

Alternatively, the sentence could be relaxed and given more impact with a revision such as "High school students who carry into college a poor understanding — or, worse, no understanding at all — of evolution are less likely to pick careers in the biological and geological sciences." (Note the relocation of the flexible modifying phrase "into college" to smooth out the syntax.)

10. "Hindu believers are governed by the three doctrines of dharma or universal law, karma or the cumulative effects of personal actions, and samsara or the cycle of rebirth."
Always set terms off from their glosses, or brief definitions (See? I just glossed gloss), by a set of parenthetical commas; both in this explanation and in the sample sentence, the sentence structure requires a semicolon in place of the closing comma: "Hindu believers are governed by the three doctrines of dharma, or universal law; karma, or the cumulative effects of personal actions; and samsara, or the cycle of rebirth." (A simple gloss would look like this: "Dharma, or universal law, is integral to both Hinduism and Buddhism.")

Thanks To Mark Nichol / Daily Writing Tips
http://www.dailywritingtips.com/10-comma-cases-in-which-more-is-more/