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Is it a flying comma,[br]or a quotation mark chopped in half?

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Either way, you may already be well-versed[br]in how to use the apostrophe,

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but here's a quick refresher on its usage.

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The apostrophe can be used in three ways:

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to mark possession,

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to mark contraction,

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to mark the plural of single letters.

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Most of the time, if you see an apostrophe[br]hovering helpfully near a word,

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it's trying to mark possession [br]or contraction.

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First, let's look at how the apostrophe[br]marks possession.

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As you can see, the placement[br]of this punctuation mark

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can really change [br]the meaning of a sentence.

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"Those robots in [br]the sand are my sister's."

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"Those robots in [br]the sand are my sisters.'"

0:00:56.596,0:01:00.799
"Those robots in the sand are my sisters."

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When showing possession, the apostrophe[br]belongs next to the noun

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that owns or possesses something.

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The noun can be singular or plural.

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Proper nouns work, too.

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So if Lucy needs to get her robots[br]under control before they cause mayhem,

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those dangerous creatures [br]would be "Lucy's robots."

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But what if Lucy was Lucas?

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Would we write "Lucas' robots"[br]or "Lucas's robots"?

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And what if Lucas gave his robots[br]to the Robinsons family?

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Would it be "The Robinsons' robots,"[br]or "The Robinsons's robots"?

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The truth is, even grammar nerds[br]disagree on the right thing to do.

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The use of 's after a proper noun[br]ending in s is a style issue,

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not a hard and fast grammar rule.

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It's a conundrum [br]without a simple answer.

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Professional writers solve this problem[br]by learning what's considered correct

0:01:54.640,0:01:57.401
for a publication, and doing that.

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The important thing is to pick one style

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and stick with it [br]throughout a piece of writing.

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One more wrinkle.

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Certain pronouns already [br]have possession built in

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and don't need an apostrophe.

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Remembering that will help you avoid one[br]of the trickiest snags in English grammar:

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its vs. it's.

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"It's" only take an apostrophe when it's[br]a contraction for "it is" or "it has."

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If you can replace "it's" with [br]one of those two phrases,

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use the apostrophe.

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If you're showing possession, [br]leave it out.

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Otherwise, contractions [br]are pretty straightforward.

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The apostrophe stands in [br]for missing letters,

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and lets common phrases [br]squash into a single word.

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In rare cases, you can have [br]a double contraction,

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though those generally [br]aren't accepted in writing,

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with the exception of dialogue.

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So it's possessive, [br]it's often followed by s's,

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and it's sometimes tricky [br]when it comes to its usage.

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It's the apostrophe.