Questions & Answers about Pitkä poika seisoo meidän välissämme.
Why does "välissä" have the "-mme" ending added to it?
Because of the pronoun meidän (our / of us). In standard Finnish, when a postposition follows a personal pronoun, the postposition must take a possessive suffix that matches the pronoun. Since meidän corresponds to "we", we add the matching suffix -mme to välissä.
Is it strictly necessary to use both the word "meidän" and the "-mme" suffix together?
In formal or written Finnish, yes. However, in everyday spoken Finnish, people almost always drop the suffix and just say meidän välissä. On the flip side, in formal writing, you can actually drop the pronoun and just write välissämme, but keeping both is common for clarity and emphasis.
What is the base word of "välissämme" and why does it have an "-ssä" in the middle?
The base word is the noun väli, which means "space", "distance", or "middle". The -ssä part is the "in" ending. So välissä literally translates to "in the space". Many Finnish postpositions are actually just nouns in a location case!
Why does the verb "seisoo" end with a double 'o'?
The dictionary form of the verb is seisoa (to stand). To make the "he/she/it" form, you take the stem seiso- and lengthen the final vowel. That makes it seisoo (stands), which correctly matches the third-person subject poika (boy).