Learn Hardcore Korean: biga waseo jibeseo baedal jumunhaesseoyo. - It was raining, so I ordered delivery at home.

Here it’s causal: 비가 와서 집에서 배달 주문했어요 means “Because it rained, I placed a delivery order at home.” The -아서/어서 link often means “and then,” but with reasons it’s very natural and common in speech.

Why is it 와서 and not something like 오서?

From 오다 (to come), you attach -아/어서. With ㅗ/ㅏ you use -아, so 오 + 아서 → 와서 by contraction. Similarly, 오 + 아요 → 와요.

Could I use -(으)니까 or -기 때문에 instead of -아서/어서?

Yes, with nuance differences:

비가 오니까 집에서 배달 주문했어요. More “since/as,” often used when giving suggestions/commands.
비가 오기 때문에 집에서 배달 주문했어요. More formal/explanatory, sounds a bit heavier.
비가 와서… is the most neutral, conversational “because.”

Why is it 비가? Can I say 비는 or drop the particle to 비 와서?

비가 marks “rain” as the grammatical subject; that’s the default.
비는 topics/contrasts and would imply contrast (e.g., “As for rain, since it came…”), which is odd unless you’re contrasting with snow, etc.
In casual speech, people often drop the subject particle: 비 와서… This is colloquial, not wrong.

Does 집에서 mean “at home” or “to home”?

집에서 marks the location where the action happens: you ordered while at home. If you want to highlight the destination of delivery, use:

집으로 (배달을) 시켰어요. (ordered delivery to home; “toward home”)
집에 시켰어요. is also heard, but 집으로 is more precise for destination.

Can I move 집에서 earlier in the sentence?

Be careful. 집에서 비가 와서… means “because it rained at home,” which is odd. Keep 집에서 next to the verb it modifies:

Natural: 비가 와서 집에서 주문했어요.
Odd: 집에서 비가 와서 주문했어요. (sounds like it only rained at your house)

Is 배달 주문했어요 natural? How does it compare with 배달을 시켰어요 or 배달음식 시켜 먹었어요?

배달 주문했어요 = “I placed a delivery order” (neutral; used for apps/groceries/food).
배달을 시켰어요 = very common for ordering delivery.
배달음식 시켜 먹었어요 = specifically “ordered delivery food and ate it,” very idiomatic for food.

Is 배달 주문 redundant (like “delivery order”)?

No. 주문 is “order,” and 배달 주문 specifies the type of order (delivery vs. pickup). Similar sets exist like 포장 주문 (“takeout order”).

Do I need the object marker? Should it be 배달 주문을 했어요?

Both are fine:

배달 주문했어요 (object omitted in a light-verb construction; very common).
배달 주문을 했어요 (more explicit or careful). You can also hear 배달을 주문했어요; all are acceptable in everyday speech.

Could I just say 주문했어요 and omit 배달?

Yes, but it then just means “I ordered [something].” In a food context, listeners may infer delivery from context, but it’s less specific (could be pickup or dine-in pre-order).

Pronunciation tips for the whole sentence?

비가 와서: [비가 와서]
집에서: [지베서] (ㅂ liaison: 집 + 에서 → 지베서)
주문했어요: [주문해써요] (했어요 is pronounced like 해써요) Put it together smoothly: [비가 와서 지베서 배달 주문해써요].

What register is -했어요? How would this change in casual or formal speech?

Polite informal (default): …주문했어요.
Casual/between friends: …주문했어.
Formal/polite (announcements/reports): …주문했습니다.

Can I use -아서/어서 before commands or suggestions?

Textbooks advise using -(으)니까 for reasons before imperatives/proposals:

Better: 비가 오니까 우산 가져가세요.
Less standard: 비가 와서 우산 가져가세요. In casual speech you’ll hear both, but -(으)니까 is the safer choice for requests/commands.

What about 와 가지고/와가지고? Is that okay?

Yes, it’s a colloquial alternative for reasons:

비가 와가지고 집에서 배달 주문했어요. It’s informal/regional in feel. Avoid it in formal writing.

Could I split into two sentences with 그래서?

Absolutely:

비가 왔어요. 그래서 집에서 배달 주문했어요. This is very natural and beginner-friendly.

Any quick synonyms or small tweaks to sound more native?

Add intensity: 비가 많이 와서…
Use the very common verb: 비가 와서 집에서 배달 시켰어요.
For food specifically: 비가 와서 집에서 배달음식 시켜 먹었어요.

What’s the difference between 배달하다, 배달을 시키다, and 주문하다?

배달하다: “to deliver” (what the courier/restaurant does).
배달을 시키다: “to order delivery” (what the customer does).
주문하다: “to place an order” (general; can be delivery, pickup, goods, etc.).