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act one's age

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Behave more maturely. Although the phrase often is used in asking children to act in a more grown-up fashion (Only babies suck their thumbs; act your age), it also may refer to an adult who is, sometimes deliberately, acting much younger than might be considered appropriate (Grandpa, it's time you stopped climbing ladders and acted your age).

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Apostrophes can be tricky; prove you know the difference between it’s and its in this crafty quiz!
Question 1 of 12
On the farm, the feed for chicks is significantly different from the roosters’; ______ not even comparable.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
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