Learn Hardcore Korean: jaryoreul boksahaeseo gyosunimkke jechulhaeya haeyo. - You have to copy the materials and submit them to the professor.

를 is the direct-object marker. It tells us that 자료 (“materials”) is what’s being acted upon by the verbs 복사하다 (“to copy”) and 제출하다 (“to submit”). After a vowel-ending noun like 자료, you use 를 (after a consonant, you’d use 을).

What does 복사해서 mean and why is -아서 used here?

복사해서 comes from 복사하다 + the connective ending -아/어서. It literally means “having copied” or “copy and then….” The -아서/어서 form links two actions in sequence (or sometimes shows reason). Here it indicates “copy (자료) and then submit.” Because 복사하다 ends in 하, -아서 becomes -해서 (so 복사하 + 아서 = 복사해서).

Can I use 복사하고 교수님께 제출해야 해요 instead of 복사해서 교수님께 제출해야 해요?

Yes. -고 also connects sequential actions (“copy and then submit”). The nuance is subtle: -아서/어서 can suggest purpose or method (“by copying…”), while -고 is a neutral sequence connector. In everyday speech, both are perfectly acceptable here.

Why is 교수님께 used rather than 교수님에게 or 교수님한테?

께 is the honorific dative marker used when the recipient is someone you respect (like a professor). 에게 is neutral, and 한테 is informal/slangy. Because you’re addressing the professor respectfully, you use 교수님께.

What does 제출해야 해요 mean, and how does the grammar pattern -아/어야 하다 work?

제출해야 해요 means “must submit” or “have to submit.” The pattern verb stem + -아/어야 하다/되다 expresses obligation or necessity (“need to…”). Here:
• 제출하다 → 제출하 + 어야 하다 → 제출해야 하다
• In polite speech, 하다 → 해요, giving 제출해야 해요.

Could I say 제출해야 돼요 instead of 제출해야 해요? What’s the nuance?

Yes. -아/어야 되다 also expresses obligation. Many Koreans use 제출해야 돼요 and 제출해야 해요 interchangeably. Some see -해야 돼요 as “external requirement” and -해야 해요 as “personal obligation,” but in daily conversation there’s little practical difference.

Why is there no subject like 저는 in this sentence?

Korean often omits subjects (and objects) when they’re obvious from context. Here it’s clear you’re talking about what you yourself must do, so 저는 isn’t necessary.

What is the politeness/formality level of -해야 해요? How can I make the sentence more formal?

-해야 해요 is polite speech (존댓말) at the standard everyday level. To switch to a more formal or written style (격식체), you could say:
• 자료를 복사하여 교수님께 제출해야 합니다.
Here -하여 is the formal connective (instead of -해서) and -합니다 is the formal declarative.

How would I change this to express past obligation, like “I had to copy and submit”?

Keep 복사해서 and turn 해야 해요 into the past 해야 했어요:
자료를 복사해서 교수님께 제출해야 했어요.
This means “I had to copy the materials and submit them to the professor.”

How would I express a future obligation, like “I will have to copy and submit”?

Use -아/어야 할 거예요 for future necessity:
자료를 복사해서 교수님께 제출해야 할 거예요.
This translates as “I’m going to have to copy the materials and submit them to the professor.”