It depends on what words come after and how you're using it in the sentence.
Example:
My ancestors came from Italy.
My ancestors' curly hair is beautiful.
If it is possessive (owning something), use the apostrophe. If not, don't use one.
No, the word "ancestors" does not need an apostrophe. The word "ancestors" is already plural and does not show possession.
No, Korean language does not use apostrophes in its writing system.
No, "Doc Adams" does not need an apostrophe unless it is possessive, such as "Doc Adams's bag."
No, there shouldn't be an apostrophe in "horses" as it is a plural noun. The sentence is correct as "the horses stalls are clean."
No, the word "says" does not need an apostrophe. It is the third person singular form of the verb "to say."
No, you do not need to put an apostrophe in the word "hundreds" unless you are indicating a contraction or possession.
I am does not need an apostrophe. It is only when you make it into a contraction by dropping the a that you need the apostrophe. It becomes I'm in that situation.
No, Korean language does not use apostrophes in its writing system.
No. The Cannons doesn't need an apostrophe.
No, Christmas Eve does not need an apostrophe.
No, because plurals do not need an apostrophe.
No, there shouldn't be an apostrophe in "horses" as it is a plural noun. The sentence is correct as "the horses stalls are clean."
As a plural, for more than one dad; no, does not need an apostrophe. As a possessive, as in the item belonging to dad, then yes, it does need an apostrophe.
No. Harringtons doesn't need an apostrophe.
The plural "Thursdays" doesn't need an apostrophe.
Lost wages doesn't need an apostrophe.
No, ours does not need an apostrophe (ever).The piano at the church had been ours.
If you're talking about more than one employee, then don't use an apostrophe. Plural words should never have an apostrophe. If you're talking about something that belongs to a single employee (such as "the employee's computer") then you need an apostrophe.