Questions & Answers about Koira syö valkoista kalaa.
Why are both valkoista and kalaa in the partitive case?
In Finnish, an adjective must match the case of the noun it describes. Since the dog is eating an unspecified amount of fish as food, kala (fish) takes the partitive ending to become kalaa. Because they are a pair, the adjective valkoinen (white) must also take the partitive case to become valkoista.
How do we get valkoista from the basic word valkoinen?
Finnish words ending in -nen have a special rule. To make them partitive, you drop the -nen ending and add -sta. So, the basic adjective valkoinen becomes valkoista.
Why use the partitive case for fish here instead of the basic form kala?
We use the partitive because fish here is an uncountable mass of food, meaning 'some fish'. If the dog ate a whole, specific single fish, you would use a different case to show that the action has a complete object.
If the dog was eating one whole white fish, would the adjective still match the noun?
Yes! Adjectives always follow the noun. If the dog ate one whole fish, the noun would change to kalan, so the adjective would have to match its ending and become valkoisen.