Why progressive tense (～ている) is not used in this case?


I was reading something which is supposed to mean "Why is it moving?". I would
translate it as なんで動いているか？ but it actually says なんで動いてんだ？

What's the difference between them? I think I cannot capture that nuance.

I think that 動いている it's something that it's moving at this time whereas 動いてんだ
sounds more like I'm stating that it's moving, but I find the lack of tense
disturbing (maybe it's a very strong statement implying surprise).

Another question: Could I even say なんで動いてんだった？ meaning "why was it moving?"
instead of なんで動いていたか？




~てんだ is just a spoken contraction of ~ている の だ, so you have your continuous
tense, and also a のだ, which is sort of an exclamation mark added to the
question.




~てんだ is just a spoken contraction of ~ている の だ, so you have your continuous
tense, and also a のだ, which is sort of an exclamation mark added to the
question.

