Learn Croatian: Zatvori prozor i ne gasi televizor! - Close the window and do not turn off the television!

This sentence perfectly shows how Croatian uses verb aspects in commands. For positive commands like "Close!", we usually want the action completed, so we use the perfective verb zatvoriti. For negative commands like "Do not turn off!", we almost always use the imperfective verb gasiti because we are telling someone not to even be in the process of doing the action.

If I wanted to tell someone to actually turn off the TV, would I still use gasi?

No! If you give a positive command to turn it off, you want the action completed, so you must switch to the perfective aspect of the verb, which is ugasiti. The command would be: Ugasi televizor!

I thought the verb gasiti meant "to extinguish". Why is it used for a TV?

You are right! Originally, gasiti means to put out or extinguish a fire. In modern Croatian, it is the standard everyday word for turning off lights, appliances, and electronic devices like a televizor. Interestingly, to turn something on, you use the opposite verb paliti, which literally means to ignite or set on fire!

Why do the words prozor and televizor look exactly like their dictionary forms if they are direct objects?

They are actually in the accusative case because they are the direct objects receiving the action of the verbs. However, as a quick refresher: for masculine nouns that represent inanimate objects (things, not living beings), the accusative form is identical to the nominative (dictionary) form.