When expressing ‘would have done’ or ‘probably has done’ in English, this more or less corresponds to the Korean Past-Future using -겠- (-kett-) attached to a past base reagrdless if plain past or honorific past. Below shows the progression of verb ‘go’ from plain base to past base to past future base while the next one is the progression in honorific form:
- 가 (ka) -> 갔 (katt) -> 갔겠 (kattkett)
- 가시 (kashi) -> 가셨 (kasyeott) -> 가셨겠 (kasyeottkett)
Here are some uses in a sentence:
- 돈이 만히 들었겠어요. (Doni manhi deureottkesseoyo) It must have cost a lot.
- 어빠가 벌써 했겠어요. (Oppaga beolsseo haettkesseoyo) Brother will have already done it
In this sentence, the past marker gives the meaning as the English verb has or have while the future marker gives it a meaning of probably.
This may sound a bit confusing for non native speaker of Korean when you compare the future form versus the past-future. The only difference is probably on how ‘ㄱ’ will sound. Lile in the example 가, in simple future this is 가겠어요 would be pronounced more like kagesseoyo (ㄱis more on the g sound since it is sandwich between 2 vowel sounds). For the past-future this is 갔겠어요 which is pronounced as katkesseoyo where t in most cases will be swallowed so you would only hear kakesseoyo.