Breakdown of Heidän täytyi evakuoida rakennus tulipalon takia.
he
they
täytyä
to have to
tulipalo
fire
rakennus
the building
Questions & Answers about Heidän täytyi evakuoida rakennus tulipalon takia.
Why is the verb täytyi in the singular form when the subject is 'they'?
Verbs of obligation like täytyy and its past tense täytyi never change to match the number or person of the subject. They always stay in the third-person singular form. Instead of changing the verb, Finnish changes the subject into the genitive case (here, heidän instead of he).
Could I use piti instead of täytyi in this sentence?
Yes! Piti is the past tense of pitää (to have to) and means exactly the same thing as täytyi in this context. Heidän piti evakuoida... is very common and perfectly correct.
Why doesn't the object rakennus have the -n ending normally used for total objects?
This is a special rule for necessity sentences. When you use an obligation verb like täytyi, a whole object (one that would normally get the -n accusative ending) is instead put in the basic nominative form. So we say rakennus, not rakennuksen.
How does the phrase tulipalon takia work?
Takia is a postposition that means 'because of'. Like most Finnish postpositions, it requires the noun attached to it to be in the genitive case. That is why tulipalo (fire) gets the -n ending to become tulipalon.