Learn Hardcore Korean: eoje chinguwa gilge iyagihaesseoyo. - I talked with a friend for a long time yesterday.

와/과 links nouns and can mean either “and” or “with.” With verbs like 이야기하다 (to talk), 친구와 means “with a friend.” Formally, use 와 after a vowel (친구+와) and 과 after a consonant.

Can I use 친구랑 or 친구하고 instead of 친구와?

Yes. They all mean “with a friend,” but differ in register:

친구와/과: more formal/written.
친구하고: neutral, very common in speech.
친구랑/이랑: casual speech. Example: 어제 친구랑 길게 이야기했어요.

Do I need 같이 after 친구와?

Not required. 친구와 already implies “with.” Adding 같이 (“together”) is fine for emphasis: 어제 친구와 같이 길게 이야기했어요.

What’s the difference between 길게 and 오래 here?

Both can describe duration, but nuance differs:

길게 (from 길다, “long”): “at length,” focusing on the extended nature of the talk.
오래: “for a long time,” focusing on duration. Both are natural with 이야기하다: 길게/오래 이야기했어요. You can also say 오랫동안 이야기했어요 for “for a long period.”

How is 길게 formed, and can I do this with other adjectives?

길게 is the adverb form of 길다 made with -게. Many adjectives form adverbs this way:

빠르다 → 빠르게 (quickly)
느리다 → 느리게 (slowly)
조용하다 → 조용하게 (quietly) Note some adverbs have preferred forms (e.g., 쉽게, 편하게), and in spoken Korean -게 can be dropped in set phrases.

Where can 길게 go in the sentence?

Adverbs usually come before the verb. Common placements:

어제 친구와 길게 이야기했어요. (most natural)
어제 길게 친구와 이야기했어요. (okay) Keeping 길게 close to 이야기했어요 sounds most natural. Putting it after the verb is ungrammatical.

What’s the base form of 이야기했어요, and how is the past tense made?

Dictionary form: 이야기하다. Past polite:

하다 → 하였어요 → 했어요 (contraction) So: 이야기하다 → 이야기했어요. The -았/었- past marker contracts with 하다 to 했-.

Is 얘기했어요 different from 이야기했어요?

얘기 is a common spoken contraction of 이야기. They mean the same thing; 얘기했어요 sounds a bit more casual/colloquial than 이야기했어요.

Can I write 이야기 했어요 with a space?

Standard is to write the compound verb together: 이야기했어요. If you want a spaced version, use the object form: 이야기를 했어요. Writing 이야기 했어요 (without 를) is generally considered nonstandard.

Is it okay to say “yesterday” elsewhere in the sentence?

Time adverbs typically come early:

어제 친구와 길게 이야기했어요. (best)
친구와 어제 길게 이야기했어요. (fine) Putting 어제 at the very end is unusual in neutral speech. You can also say 어제는 (topic/contrast), often shortened to 어젠 in speech.

What politeness level is -었어요, and what are other options?

-었어요/았어요 is the polite (informal polite) style. Alternatives:

Formal polite: 이야기했습니다
Casual: 이야기했어
Plain/written narrative: 이야기했다 Choose based on setting and relationship.

How would I turn this into a question like “Did you talk at length with your friend yesterday?”

Use rising intonation (and optionally a question mark):

어제 친구와 길게 이야기했어요? (polite) More formal: 어제 친구와 길게 이야기했습니까?

How do I negate it: “I didn’t talk for long with my friend yesterday”?

Two natural options:

어제 친구와 길게 이야기하지 않았어요.
어제 친구와 오래 이야기 안 했어요. (more colloquial)

Do I need honorifics because the friend might be older?

No. The subject here is implicitly I, so you don’t add honorific -시- to the verb. If you want a more respectful word for “talk” with a respected elder, you might use expressions like 말씀 나누다 in other contexts, but for a peer 이야기하다/얘기하다 is standard.

Does 와 here mean “and” (A and B) in other contexts?

Yes. 와/과 can coordinate nouns (A and B: A와 B). In this sentence it functions as a comitative “with” because of the verb 이야기하다. You can also say A와 함께 for “together with A.”

How do I make it plural or more specific (my friend, friends)?

My friend: 제 친구와
Friends (plural): 친구들과 (optional 들)
With multiple specific people: 친구와 동료와 … (more naturally: 친구랑 동료랑 in speech)

Any pronunciation tips?

친구와 sounds like [칭구와].
이야기했어요 is pronounced [이야기해써요] due to ㅆ assimilation. Speak smoothly: 어제 친구와 길게 이야기했어요 → [어제 칭구와 길게 이야기에써요].