Questions & Answers about He syövät kalaa torstaina.
How does torstaina mean "on Thursday"?
To say that something happens "on" a certain day, Finnish adds the ending -na or -nä to the day of the week. This is called the essive case. Since Thursday is torstai, adding the ending makes it torstaina (on Thursday).
Why does torstaina use the -na ending instead of -nä?
This is because of vowel harmony. The word torstai contains the back vowels o and a. In Finnish, words with back vowels take endings with a instead of ä, so it must be -na.
Why is the word for fish kalaa instead of just kala?
Here, kala is in the partitive case, which adds the extra -a at the end. We use the partitive because eating is an ongoing action and fish here is thought of as an unspecified amount or mass noun, just like saying "They eat some fish" in English.
Why does the verb syövät end in -vät?
Verbs in Finnish must match the person doing the action. The pronoun he (they) requires the verb to have the plural ending -vat or -vät. The basic dictionary form is syödä (to eat), and for "they eat" it becomes he syövät.