-(으)ㄹ 텐데, -(으)ㄹ 테니까 and -(으)니까 Here's a comparisons of the related expressions with -ㄴ데. 1 -ㄴ데 - since/when something is happening. 비 오는데 왜 밖에 나와 있어? (Why are you standing outside in the rain?) 2 -ㄹ 건데 - since/when something will happen. 비 올 건데 왜 밖에 나와 있어? (Why are you out when it's going to rain?) 3 -ㄹ 텐데 - since/when something is expected to happen. 비 올 텐데 왜 밖에 나와 있어? (... when it's expected to rain?) And here's the expression with -니까. 1. -(으)니까 - since/because (subject) is/does ... (a direct reason). 친구는 똑똑하니까 일을 잘할 거다. 2. -ㄹ 거니까 - since/because (subject) will / is going to ... (expectation). 이 일은 내가 할 거니까 걱정 마. 3. -ㄹ 테니까 - since/because (subject) intends to / is expected to ... (expectation). 이 일은 내가 할 테니까 걱정 마. (#1 states something true now, while #2 and #3 show one's intention or future expectation. 거니까 sounds factual and 테니까 subjective, but they are often interchangeable) 터, the noun underlying 텐데 and 테니까, has both physical and abstract meaning. In the former case, it is an ordinary noun for a location or a plot of land, or a foundation for something (공터, 집터, 나루터, 일터, 터를 잡다, 터를 닦다). When used in the abstract sense, it is a dependent/bound noun which cannot be used by itself. 1. a plan(예정), guess(추측), or intention(의지) that currently stands. - 내일 갈 테니 그리 알아라 = I'll be there tomorrow (so make note of that). (plan/intention) - 시장할 터인데 어서 들어라 = Help yourself, as you must be hungry. (reason) - 나는 꼭 대학에 들어갈 테다 = I will definitely go to college. (intention) 2. a situation a person is in (처지) or circumstance/condition (형편). - 사날을 굶은 터에 찬밥 더운밥 가리겠느냐? = Having starved for three days, would I/they be picky about warm or not? - 그는 자기 앞가림도 못하는 터에 남 걱정을 한다 = He can't even take care of himself yet meddles in others' affairs.