G. J. Adler

“ A. The first declension comprises all substantives and adjectives which form their genitive in ae. The nominative of such of these words as are of purely Roman origin ends in a, that of a few Greek words in ē, ēs, and ās. Those in ā and ē are mostly feminine, the rest are masculine. ”

“ But the Romans frequently reply by a simple repetition of the verb or of the emphatic word of the inquiry, e.g. here with a simple Habeō and Est.—The ceremonious use of a word like our "Sir" was unknown to the ancients. ”

“ Words of the neuter gender have the nominative, accusative, and vocative, singular and plural always alike. D. Rule. Adjectives and adjective pronouns agree with their substantives in gender, number, and case. ”