You do not need an apostrophe here. Theirs is already in the right form. Their by itself is plural, because you are saying their book, meaning more than one person who owns the book. You only need to add 's, when you are dealing with singular words. The building's tenth floor was on fire.
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The first three sentences of the above answer are correct; the latter two are incorrect and irrelevant...
"They" (as with "him", "her", and "it") is a pronoun, therefore it does not require an apostrophe to be made possessive (i.e., the possessive forms of the above are "theirs", "his", "hers", and "its").
For more detail on apostrophes as indicators of possession:
If it is singular, add "'s" (apostrophe s).
If it is plural and ends in "s", add "s'" (s apostrophe). This is most plurals.
If it is plural but does not end in "s" (ex. "children", "men"), add "'s" (apostrophe s).
If it is plural but does not end in "s", but is the same as the singular (ex. "elk" is plural of "elk", therefore "elk's" is singular and "elks'" is plural).
No, the possessive form of "they" is "their," without an apostrophe. "Their's" is incorrect.
No, "theirs" is a possessive pronoun that does not require an apostrophe to show possession.
No, "theirs" is a possessive pronoun and does not require an apostrophe. The apostrophe is used in contractions or to show possession, but not in this case.
No, the apostrophe should come before the "s" in "fisherman's" to indicate possession by a singular fisherman.
Pronouns do not require an apostrophe to indicate possession. Instead, possessive pronouns such as "its," "hers," and "theirs" already show ownership without needing an apostrophe.
In the possessive pronouns "theirs" and "hers," the "s" already indicates possession, so apostrophes are not needed. Including an apostrophe, such as in "theirs" or "her's," would be grammatically incorrect.
No, "theirs" is a possessive pronoun that does not require an apostrophe to show possession.
No, the apostrophe should come before the "s" in "fisherman's" to indicate possession by a singular fisherman.
Yep :)
Yes, the apostrophe is in the correct place. "Their" is possessive, indicating that the book belongs to them, and the apostrophe comes before the s to show possession. So, "their book's" is correct.
Yes, and you've put it in the right place
Yes, but you mis-spelt apostrophe.
If you are intending to refer to a uniform that belongs to a man, then the correct placement of the apostrophe is as you have it. This is called the possessive form.
No, "theirs" is a possessive pronoun and does not require an apostrophe. The apostrophe is used in contractions or to show possession, but not in this case.
The apostrophe in a contraction holds the place of a letter or group of letters. Example: Don't = Do not (the apostrophe holds the place of the 'o') They've = They have (the apostrophe holds the place of the 'ha')
The possessive form of it is "its." Notice that there is no apostrophe. "It's" is a contraction for "it is" or "it has." "Its" without an apostrophe is the possessive form of it. The same holds true for his, hers, ours, and theirs -- none of these have apostrophes.
Possessive pronouns do not take apostrophes. Some examples of possessive pronouns are: its, hers, his, theirs.
"Can not" is "can't" when an apostrophe is used to signal that a shortening has taken place.