Learn Finnish: Miksi nainen kieltäytyy tupakoimasta? - Why does the woman refuse to smoke?

In Finnish, the verb kieltäytyä (to refuse) requires the following verb to be in the third infinitive elative form (-masta / -mästä). You can think of it literally as refusing from doing something.

How do you build the form tupakoimasta?

First, find the strong stem of the verb tupakoida (to smoke), which is tupakoi-. Then, add the third infinitive marker -ma- and the elative case ending -sta (meaning 'out of' or 'from'). Put together, it makes tupakoimasta.

If she refused a thing instead of an action, would it also use the -sta ending?

Yes! The verb kieltäytyä always demands the elative case (-sta / -stä). If she refused dessert, it would be Nainen kieltäytyy jälkiruoasta (The woman refuses the dessert).

I know the verb kieltää means 'to forbid'. How is kieltäytyä related to it?

Kieltäytyä is the reflexive version of kieltää. While kieltää means you forbid someone else from doing something, kieltäytyä means you decline or refuse to do it yourself.