The possessive form for the plural noun countries is countries' (just as you have it in your question).
Example: All of the countries' flags surrounded the field.
The singular possessive form for country is county's.The plural form is counties; the plural possessive form is counties'.
The plural form for the noun county is counties; the plural possessive form is counties'.Example: The counties' joint task force meets every Wednesday.
The plural form of the noun county is counties.The plural possessive form is counties'.Example: All of the counties' representatives have been seated.
Yes, counties' is the possessive form of the plural noun counties. example: Not all of the counties' sales taxes are at the same rate.
Yes, "counties'" is the plural possessive form of "county." It indicates that something belongs to or is associated with multiple counties.
The singular possessive form is heart's; the plural possessive form is hearts'.
The plural form is founders. The plural possessive is founders'.
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.
The singular possessive form for the noun knife is knife's.The plural form is knives; the plural possessive form is knives'.
The noun 'sister' is not plural and is not possessive.The plural form is sisters.The possessive form is sister's.The plural possessive form is sisters'.
The singular form is goose; the singular possessive form is goose's.The plural form is geese; the plural possessive form is geese's.
The plural possessive form of "cherubim" is "cherubim's."