Hi Mike and Chris,
Adding more salt and pepper to the soup, so stir it well!
I am studying at Livemocha in parallel and have come across similar situations in some exercises and deduced to myself that gender matching in the sentence is what matters. Don't take this as a definite answer, my conclusion may be wrong.
Consider these examples (though in negative, which may be a different case):
Αυτή δεν είναι καρέκλα. Αυτό είναι τραπέζι.
Αυτή δεν είναι λάμπα. Αυτός είναι καναπές.
Where the person knows beforehand that the referred object is not feminine (neuter and masculine respectively), nevertheless he uses Αυτή to negate the feminine noun.
So judging from this, your sentences probably should be
Η γάτα μου ονομάζεται Ζον και αυτή είναι μεγάλη.
Αυτό είναι το μωρό μου/ το παιδί μου.
Ο Γιάννης είναι το παιδί μου. Αυτό είναι το παιδί μου.
regardless of John's and Yanni's gender.
More salt and pepper... consider these sentences:
Αυτή είναι γραμματέας.
Αυτή είναι μηχανικός.
where γραμματέας (secretary) and μηχανικός (mechanic) evidently are masculine while the person is a woman (Αυτή). I assume that this may be an exception, where γραμματέας and μηχανικός have no feminine form???
I like brainstorming!
Να έχετε μια όμορφι μέρα.
Arshak |