Learn Croatian: Ako probušiš gumu, moraš promijeniti zračnicu. - If you puncture the tire, you must change the inner tube.

In Croatian, perfective verbs generally cannot be used to describe actions happening right now. However, they are frequently used in the present tense immediately after ako (if) to describe an action that might be completed in the future. English does something similar by using the standard present tense for future conditionals.

I see the root of zračnicu is related to zrak (air). How does this suffix work?

The dictionary form is zračnica (used here in the accusative case as zračnicu). It combines zrak (air) with the suffix -nica, which is highly productive in Croatian for forming nouns that denote objects, containers, or rooms associated with the root word. It literally translates to an air container, which perfectly describes an inner tube.

Why do we use the perfective verb promijeniti instead of its imperfective pair mijenjati?

You use the perfective promijeniti because you are talking about completing a single, specific task to fix the tire. If you used the imperfective mijenjati, it would shift the focus to the continuous process or duration of changing it, rather than focusing on the finished result of the action.

Is there a reason promijeniti comes right after moraš instead of at the end of the sentence?