There are two accepted forms for possessive singular nouns ending in s:
Add an apostrophe (') after the existing s at the end of the word: Matthew Kitsos'
Add an apostrophe s ('s) after the existing s at the end of the word: Matthew Kitsos's
Examples:
We met Matthew Kitsos' parents at the meeting.
We met Matthew Kitsos's parents at the meeting.
The possessive form of the singular noun baby is baby's.Example: The baby's name is Matthew.
The possessive singular noun is explorer's. The possessive plural noun is explorers'.
The possessive form for the noun coyote is coyote's.
The possessive form of zoo is zoo's.
The possessive form for the noun preacher is preacher's.
The possessive form for the noun laboratory is laboratory's.
No, he is not possessive. The possessive form would be his.
The possessive form for the noun oxygen is oxygen's.
The possessive form for the noun coyote is coyote's.
The possessive form is grandson's.
The possessive form is island's.
No, it is a singular possessive noun.