In short

To frame an action as a favour - something you do for someone else’s benefit - build the 아/어 form of the verb and add 주다 (juda, give). Use plain 주다 for an equal or a junior, humble 드리다 (deurida) when the person you help is a superior, and 주시다 (jusida) when a superior does something for you. This same machine builds polite requests (열어 주세요, please open it) and offers (도와줄게요, I’ll help you).

The rule

Korean does not just say what happens; it can also say who it is for. You take the 아/어 conjunctive form you learned in lesson 10 and stack a “giving” auxiliary onto it. The direction of the favour picks the auxiliary.

Step 1 - Build the 아/어 form, then add 주다

The pattern is Verb (아/어 form) + 주다. The auxiliary carries all the tense and politeness; the main verb just sits in its bare 아/어 shape and never takes the negation - the long form goes on the auxiliary (열어 주지 않았어요, yeoreo juji anasseoyo, never *열지 않아 줬어요) while the short 안/못 stands in front of the whole block (안 열어 줬어요, an yeoreo jwosseoyo).

• 사다 (sada, buy): 사 + 줘요 -> 사 줘요 (sa jwoyo, I buy it for you).
• 열다 (yeolda, open): 열어 + 줘요 -> 열어 줘요 (yeoreo jwoyo, I open it for you).
• 하다 (hada, do): 해 + 줘요 -> 해 줘요 (hae jwoyo, I do it for you).

Remember the contraction: 주 + 어요 -> 줘요, never *주어요.

Step 2 - Why the plain verb can sound cold

Compare 문을 열어요 (Muneul yeoreoyo, I open the door) with 문을 열어 줘요 (Muneul yeoreo jwoyo, I open the door for you). The first only reports the event; the second says you did it as a kindness to the listener. Where English leans on tone of voice, Korean marks the favour in the grammar - so a bare 기다려요 as a request can feel like a flat command, while 기다려 주세요 is warm and polite.

Step 3 - Pick the auxiliary by direction (uses lesson 22)

Three auxiliaries, three directions:

• 주다 - level or downward. You do it for an equal or a junior: 친구한테 사 줬어요 (Chinguhante sa jwosseoyo, I bought it for my friend).
• 드리다 - upward, humbling yourself. You do it for a superior; the beneficiary takes 께: 부모님께 사 드렸어요 (Bumonimkke sa deuryeosseoyo, I bought it for my parents).
• 주시다 - a superior does it for you. This is 주다 + the honorific -(으)시-, so the honored giver takes 께서: 선생님께서 설명해 주셨어요 (Seonsaengnimkkeseo seolmyeonghae jusyeosseoyo, the teacher explained it for me).

The beneficiary’s particle is the dative from lesson 20: 한테/에게 for an equal, 께 for a superior.

Step 4 - Requests and offers

Because 주다 already means give (me a favour), requests are built right on it, and they get softer the longer they are:

• -아/어 주세요 - the standard polite request: 열어 주세요 (yeoreo juseyo, please open it).
• -아/어 주시겠어요? - softer, would you…?: 도와주시겠어요? (dowajusigesseoyo?, would you help me?).
• -아/어 주실 수 있어요? - tentative, could you…?: 열어 주실 수 있어요? (yeoreo jusil su isseoyo?, could you open it?).

To offer, use the promise ending -(으)ㄹ게요 from lesson 43: -아/어 줄게요 for an equal (제가 도와줄게요, Jega dowajulgeyo, I’ll help you), -아/어 드릴게요 for a superior (제가 들어 드릴게요, Jega deureo deurilgeyo, I’ll carry it for you).

Step 5 - Lexicalized benefactives

A few of these have fused into single dictionary words and are written with no space: 도와주다 (dowajuda, help), from ㅂ-irregular 돕다 (돕 -> 도와), and its humble twin 도와드리다 (dowadeurida) - 표준국어대사전 lists it as the 높임말 of 도와주다. Others - 가르쳐 주다 (gareuchyeo juda, teach it for someone) and 알려 주다 (allyeo juda, let someone know) - are not dictionary words at all, so they follow the ordinary auxiliary rule: spaced is the norm, joined is tolerated. This lesson keeps the space.

Forms & patterns

The 아/어 form + the two auxiliaries you build yourself (해요체):

The three directions (who acts, who benefits, which particle):

Requests and offers (softer as you go down):

Giving and receiving vocabulary (the 겸양어·존경어 pairs behind lesson 22’s 특수 높임말):

Examples

Common mistakes

• 부모님한테 꽃을 사 줬어요. (Bumonimhante kkocheul sa jwosseoyo.) -> 부모님께 꽃을 사 드렸어요. (Bumonimkke kkocheul sa deuryeosseoyo.) - When you do a favour for someone you honour, the beneficiary takes 께 and 주다 becomes humble 드리다. The two move together.
• 선생님이 저한테 한국어를 가르쳐 드렸어요. (Seonsaengnimi jeohante Hangugeoreul gareuchyeo deuryeosseoyo.) -> 선생님께서 저한테 한국어를 가르쳐 주셨어요. (Seonsaengnimkkeseo jeohante Hangugeoreul gareuchyeo jusyeosseoyo.) - When the honoured person is the giver, raise the subject with 주시다 (and mark it with 께서). 드리다 would say the teacher humbles herself to you - backwards.
• 제가 창문을 열어 주셨어요. (Jega changmuneul yeoreo jusyeosseoyo.) -> 제가 창문을 열어 드렸어요. (Jega changmuneul yeoreo deuryeosseoyo.) - 주시다 honours the giver, so using it about yourself honours yourself. For a favour you do for a superior, use humble 드리다.
• 잠깐만 기다려요. (Jamkkanman gidaryeoyo.) -> 잠깐만 기다려 주세요. (Jamkkanman gidaryeo juseyo.) - A bare 기다려요 aimed at someone can land as a cold command; -아/어 주세요 frames it as a polite favour.
• 책를 읽어 줬어요. (Chaegreul ilgeo jwosseoyo.) -> 책을 읽어 줬어요. (Chaegeul ilgeo jwosseoyo.) - 책 ends in a 받침, so the object particle is 을, not 를. Check every allomorph against the actual word.

Tips

• Bare verb = fact, +주다 = favour. 열어요 just describes the event; 열어 줘요 gives it to the listener. Korean marks kindness in the grammar where English uses tone - so leaving 주다 off can sound curt.
• A direction compass. 드리다 points up (I bow to a superior), 주시다 points down to me (a superior helps me), 주다 is level. Pair 께 with 드리다, and 께서 with 주시다.
• Longer request = softer request. 주세요 -> 주시겠어요? -> 주실 수 있어요?: each adds distance and politeness. Reach for the longer one with strangers and superiors.
• 도와주다 and 도와드리다 are each a single word. 돕다 is ㅂ-irregular (돕 -> 도와), and both compounds sit in 표준국어대사전 written joined, so 도와줘요 and 도와드려요 take no space. Other benefactives (가르쳐 주다, 알려 주다) are not dictionary words and are fine either joined or spaced.