Punctuation Exercise (529)

In each sentence, revise one or more punctuation marks to reflect correct usage.

Answers and Explanations

1.
Original: There are some good action sequences; some amusing twists; some easily digestible sociological and philosophical points, and a thoroughly satisfactory surprise ending.
Correct : There are some good action sequences, some amusing twists, some easily digestible sociological and philosophical points, and a thoroughly satisfactory surprise ending.

Using semicolons for a simple in-line list (one contained within a sentence) is excessive; commas are sufficient. When semicolons are used in such a list (when at least one of the list items itself has at least one comma within it), they should be used consistently; the comma before the final phrase should be a semicolon as well.

2.
Original: Former hostage Javier Espinosa who had been held in Syria by Islamic State extremists has described mock executions and other forms of psychological torture.
Correct : Former hostage Javier Espinosa, who had been held in Syria by Islamic State extremists, has described mock executions and other forms of psychological torture.

The phrase describing the circumstances of Espinosa’s confinement is a parenthetical phrase—one that can be excised from the sentence without affecting the grammatical structure of the main clause—and should therefore be bracketed by a pair of commas (or by parentheses or two dashes).

3.
Original: Five years of research culminated in the identification of a gene that was previously associated with the cell cycle, specifically CHEK2.
Correct : Five years of research culminated in the identification of a gene that was previously associated with the cell cycle—specifically, CHEK2.

"Specifically" must be set off by a comma from the gene name that follows it. The tag phrase "specifically, CHEK2" should, in turn, be set off from the main clause, but doing so with the same punctuation mark as the one separating the two words in the phrase would obscure the sentence’s organization, so a stronger punctuation mark—a dash—should set the tag phrase off.

4.
Original: Early on, some U.S. cities changed clocks on different days for different reasons but this just threw train timetables into chaos which led to the Uniform Time Act of 1966.
Correct : Early on, some US cities changed clocks on different days for different reasons, but this just threw train timetables into chaos, which led to the Uniform Time Act of 1966.

A comma is required before the conjunction separating the two independent clauses that constitute this sentence. Another is required before "which" to signal that not chaos itself, but rather the inconsistent timekeeping that created the chaos, was the catalyst for the legislation. (If chaos itself were the catalyst, American English usage would require the replacement of "which" with "that"; British English does not observe this distinction.)

5.
Original: Manufacturing employment has dramatically decreased; primarily due to automation.
Correct : Manufacturing employment has dramatically decreased, primarily due to automation.

A semicolon should separate two clauses only when both clauses are independent. Here, "primarily due to automation" is not a complete thought; it is simply a phrase appended to the main clause.

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