Learn Croatian: Umjesto da jede, on povraća. - Instead of eating, he is vomiting.

English uses 'instead of' followed by an -ing verb, like 'eating'. Croatian does not have an exact equivalent for this structure. Instead, you must use the conjunction umjesto da followed by a conjugated verb. So, 'instead of eating' becomes umjesto da jede (literally: 'instead that he eats').

Could we use the infinitive here and say umjesto jesti?

No, that sounds very unnatural in standard Croatian. While you might occasionally hear an infinitive used this way in very informal or regional speech, the grammatically correct and standard way to express 'instead of doing something' is always umjesto da plus a conjugated verb.

Why is the pronoun on explicitly used in the second clause when Croatian usually drops pronouns?

Croatian usually drops subject pronouns because the verb ending already tells us who is doing the action. Here, on is included to add emphasis, balance the two clauses, and highlight the unexpected contrast between the actions.

What is the aspect of the verbs jede and povraća in this context?

Both jede (from jesti) and povraća (from povraćati) are imperfective verbs, meaning they describe an ongoing action. This matches the English translation 'is vomiting' and fits the context of an ongoing state rather than a single, completed event.