#52: Your horse is fast
Horses can be in the a or the o category — a, o
o category: water and medicine — o
Whether a possessive takes a or o depends on the relationship. A horse can be tāu if it is a pet (a-category) or tōu if it is used for transport (o-category). Most food and drink take a, but water and medicine take o. Houses, parents, and other higher relationships also take o, so we say tōu whare, tōku māmā, etc.