Children's
None are. (see the related questions below)The plural possessive of editor is editors' but it cannot take a possessive in the combined form "editor in chief" -- the plural possessive is editors in chief's.
The form childrens' is not correct.For irregular plural nouns that do not end with an s, add an apostrophe s ('s) to the end of the word (the same as a singular noun that doesn't end with s).We went to the children's playground.
The possessive form of "he" is "his": He did his homework after dinner.
No, it is singular, the possessive form of it is its. The plural form of it is they or them, and the possessive form is their.To answer the question directly: there is no such word as ITS'.
The possessive form is lawyer's.
The possessive form is whistle's.
The possessive form is posse's.
The plural possessive form is Luis's.
The singular possessive form of the noun "it" is "its". Note that there is no apostrophe in the possessive form of "it". The apostrophe is only used after "it" when used as a contraction of "it is".
The singular possessive form is heart's; the plural possessive form is hearts'.
The possessive form for the noun freedom is freedom's.
The possessive form is my sister's friend.