Questions & Answers about Sinun pitää komentaa tuhmia lapsia.
Why is the subject Sinun in the genitive case instead of the nominative Sinä?
This is a necessity sentence using the verb pitää (to have to / must). In Finnish, the person who must do something is put in the genitive case, and the necessity verb is always in the third-person singular form.
Normally, objects in a pitää sentence are in the nominative case. Why is tuhmia lapsia in the partitive case here?
You are right that total objects usually take the nominative in necessity sentences. However, the verb komentaa (to command) is a partitive verb. This means it expresses an ongoing or directed action and always requires its object to be in the partitive case, which overrides the usual necessity sentence rules.
How is the partitive plural lapsia formed from the basic word lapsi?
For old Finnish words ending in -si like lapsi, the stem changes to lapse-. To make the partitive plural, we add the plural marker -i- and the partitive ending -a, resulting in lapsia.
Why does the word for naughty (tuhmia) have the same ending as the children (lapsia)?