Learn Hardcore Korean: sukjereul kkeutnaego naseo yeonghwareul bwayo. - I watch a movie after finishing my homework.

It indicates that the first action (finishing homework) is fully completed before the second action (watching a movie) begins. It’s used to express a clear sequence of events: “after doing A, then B.”

How is -고 나서 different from just -고?

While -고 simply links verbs (like “do A and then do B” or even simultaneous actions), -고 나서 emphasizes that A is finished before B starts. -고 alone is more neutral about timing, whereas -고 나서 clearly means “only after A is done.”

Can I use -고서 or -(으)ㄴ 후에 instead of -고 나서?

Yes. -고서 is very similar (often slightly more formal), and -(으)ㄴ 후에 (e.g. 끝낸 후에) also means “after.” Nuance and formality differ: -고 나서 is conversational and neutral; -고서 is common in writing or formal speech; 후에 can be used in both formal and informal contexts.

Why is there no subject like “I” in 숙제를 끝내고 나서 영화를 봐요?

Korean frequently omits subject pronouns when they’re clear from context. Here, the speaker’s doing both actions, so adding “I” (저는) is unnecessary unless you need extra emphasis or clarity.

Why is the object marker -를 used in 영화를 봐요? Can it be dropped?

The marker -를 clarifies that 영화 is the direct object of 보다 (“to watch”). In casual speech, you might hear 영화 봐요, but including -를 is grammatically precise and makes the sentence clearer.

What level of politeness does the ending -요 convey?

The -요 ending is the polite (informal polite) style, suitable for everyday conversations with people you’re not extremely close to—strangers, coworkers, or someone slightly older than you.

How would you change this sentence to the past tense?

You transform 보다 into its past polite form 봤어요. The full sentence becomes 숙제를 끝내고 나서 영화를 봤어요, meaning “After finishing my homework, I watched a movie.”