Book cover becomes "book covers" then you add an apostrophe to make book covers'.
Hope I helped! XD
The possessive form is Amos's.
The singular possessive form is herd's.
The singular possessive form is heart's; the plural possessive form is hearts'.
The singular possessive form is lesson's.
The singular possessive form is grotto's.
The singular possessive form is week's.
The singular possessive form is classmate's.
The possessive form is Amos's.
The singular possessive form for the noun gypsy is gypsy's.
The singular possessive form for country is county's.
The singular form for the plural noun countries is country; the singular possessive form is country's.
singular possessive: boy'splural possessive: boys'
The singular possessive form is speculum's.
The singular possessive form is contralto's.
The singular possessive form is frontiersman's.
The singular possessive form is aircraft's.
The singular possessive form is herd's.