Learn Finnish: Mä en ollu varoittanu sua, mut sä et ollu menettäny mitään. - I had not warned you, but you had not lost anything.

This sentence is written in spoken Finnish. In everyday speech, the final -t is almost always dropped from the past participle forms. In standard written Finnish, the pluperfect negative forms would be en ollut varoittanut and et ollut menettänyt.

Why is the object sua (you) in the partitive case here?

Sua is the spoken form of sinua, the partitive of sinä (you). The verb varoittaa (to warn) is a partitive verb, meaning it always forces its object to be in the partitive case, regardless of the tense or whether the sentence is negative.

What are the standard written forms for mä, sä, and mut?

Mä is the spoken form of minä (I), sä is sinä (you), and mut is a shortened spoken version of mutta (but). Recognizing these very common spoken forms is essential for understanding real-life Finnish.

Why is mitään used here for "anything"?

Mitään is the partitive form of mikään. Because the second half of the sentence is negative (et ollu menettäny), the object must be in the partitive case. Mitään is the standard pronoun used for "anything" in negative sentences, whereas a positive sentence would use a word like jotain (something).