Learn Finnish: Poika katsoo vanhoja kuorma-autoja. - The boy is looking at old trucks.

The verb katsoa (to look at) is a partitive verb. This means it describes an ongoing, continuous action, so its object must always be in the partitive case. Because the boy is looking at multiple trucks, the object is in the partitive plural. The adjective vanha (old) must match the noun in case and number, so it also takes the partitive plural form.

How does the adjective vanha change to vanhoja?

The base word is vanha. When a two-syllable word ends in -a and its first vowel is also a (like in van-), the final -a changes to an -o- before a plural ending. Then, the plural partitive marker -j- and the ending -a are added, resulting in vanhoja.

How is the partitive plural formed for kuorma-autoja?

In Finnish compound words, only the final word changes its case ending. The first part, kuorma (cargo/load), stays the same. The second part, auto, ends in -o. For words ending in -o or -u, you typically just add -ja to form the partitive plural, giving us autoja.

Could the object be kuorma-autot if he is looking at a specific, complete group of trucks?