Questions & Answers about Haluan ostaa näitä voiteita.
Why do we use näitä instead of nämä here?
Nämä is the basic plural for "these", but here we need the partitive plural näitä because you are buying an unspecified amount of the creams, not all of them. Whenever a noun is in the partitive case, the demonstrative pronoun attached to it must be in the exact same case.
The basic word for "cream" is voide. How does it become voiteita?
Words ending in -e have a weak basic form but a strong stem. Here, the weak d in voide strengthens to t. The stem ends in two e's (voitee-). To make the plural partitive, we add the plural marker -i- and the partitive ending -ta. One e is dropped to avoid having three vowels in a row, giving us voiteita.
Why does the plural partitive ending for voide become -ta instead of just -a?
The ending is -ta because after adding the plural -i- to the stem voitee-, we end up with the vowel combination -ei-. Stems that end in two vowels (a diphthong) take the -ta or -tä partitive ending instead of just a single vowel.
Why is ostaa in its basic dictionary form?