I know in Korean, ㄴ/는다고 하다 can be shortened to ㄴ/는대요. However, what about sentences ending in past tense or honorifics? For example, I have the following 2 sentences:
흐어 씨는 어제 도서관에 갔다고 했어요:Huong said that she went to the library yesterday
선생님께서 어제 도서관에 갔다고 하셨어요: The teacher said he went to the library yesterday
How do I convert these sentences toㄴ/는대요? Thank you!
You can say:
(A) 흐어 씨는 어제 도서관에 갔대요/갔댔어요.
(B) 선생님께서 어제 도서관에 가셨대요/가셨댔어요.
B is technically different, because it's a contraction of "선생님께서 어제 도서관에 가셨다고 했어요," but assuming it's the teacher talking about themself going to the library, it should work.
When you think about it, there are actually four combinations:
도서관에 간대요/가신대요 = they say they're going to the library
도서관에 간댔어요/가신댔어요 = they said they were going to the library
도서관에 갔대요/가셨대요 = they say they went to the library
도서관에 갔댔어요/가셨댔어요 = they said they went to the library
(I think the final form is a bit wordy, and not very common.)
About the relative order of -시- and -ㄴ대(요), I think it's technically possible to say "도서관에 간다셔요", however, I think such a forms are rare and the opposite order (-신대요) is preferred.
On the other hand, here's an example (that I learned at middle school) where it does make a difference:
민수야, 선생님이 오시래 (X) = Minsu, the teacher is looking for you (literally, "the teacher tells you to come"
People may actually say this, but it's considered wrong because you attached -시- to the verb "오다", so it's as if the teacher is asking 민수 politely ("오세요"). The correct form should attach -시 to 하다 (tell):
민수야, 선생님이 오라고 하셔. = 민수야 선생님이 오라셔. (O)
As far as I know, in standard Korean they cannot be shortened while preserving the past tense or honorific. However, the present tense shortened forms are sometimes used even if something was said in the past. Note how even in English, saying "Huong says that she went to the library yesterday" isn't that strange even if Huong really told me this a few hours ago and I'm only relaying it to you now. In my experience this is even much more common in Korean. In general, tenses in Korean are often used in a looser way compared to English.
As a side note, in 경상도 사투리 (and maybe there are other forms in other 사투리 as well), the past tense can be included in a shortened form, e.g. "갔다고 했어"->"갔다캤어",the 고ㅎ being transformed into a ㅋ.
