English has many troublesome pairs that often perplex writers, because many words in English are similar to others but are not synonyms.

Here are some “twins” that often leave a writer wondering which one is appropriate and why.

i.e. and e.g. — Using these two-letter abbreviations might be convenient, but many people don’t know what either of them means, and other people know what each abbreviation means, but they use the wrong one to match their meaning.

The letters  i.e. are short for the Latin term id est, meaning “that is to say,” as in, “The deadline is Friday, Dec. 8, i.e, you have until midnight on that day.” The letters e.g. stand for exempli gratia (“for example”), as in “We have a full agenda for the off-site meeting, e.g., the budget, the new strategy, and changes to the production cycle.” When you want to use i.e. and e.g., use “that is” and “for example.”

Can vs couldCan expresses the physical or mental ability to do something, and it conveys a degree of certainty, as in, She can achieve whatever she focuses on, or I can be there as early as 6 a.m.

Could is the past tense of can, so it is frequently used in a past-tense context. She took the company as far as she could (took and could are both in past tense), or he wished that he could finish the book.

Could is also used as a helping verb to express a lesser degree of possibility, as in, That could be an option for us later on.

About vs around — Make it, I will be there at about 3:00, not around 3:00. The word about means approximately and nearly, as in, the project will last about three months, and She is about done with her lunch. Around means in a circle, or along a circular course, as in around-the-clock coverage. It also means “on all sides” (There was trash all around, or I looked all around for you.)

None — Many people contend that none is a short form of “not one,” so it should be followed by a singular noun, as in, None of these options is appealing. But experts say that view represents a misreading of the word’s history. None is not a contraction of not one. The word none appeared in Old English and has been used since the late 800s with both plural and singular nouns, depending on the nature of the words around it and the intended meaning of the sentence. None of the candidates are qualified is acceptable, as is None of the menu items is more than $20.

Use good resources. A dictionary and the Associated Press Stylebook, the most widely used usage manual in the U.S., are great reference tools for insight about these issues.

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Ken O’Quinn is a professional writing coach and former Associated Press writer who conducts corporate workshops on business writing, persuasive writing, and corporate communications writing. He is the author of Perfect Phrases for Business Letters (McGraw-Hill), which is available here at Amazon.com.

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