How to say things must be done, but in the past tense?

Question

I learned it from this guide, detailing 「だめ」,「いけない」 and 「ならない」constructions.

I was able to assume that the past-tense of "I must not do" is て-formはだめだった (correct me if I'm wrong), but how can I do the same for things I must do? I guess maybe it's negative て-formはだめだった, but as Tae Kim says, that's super long and thus would probably sound weird if I used it outside formal situations. Up to now, I've used the "replace なくて with なくちゃ" slang form, but how would I put that into past tense?

I was thinking about using 行けないだった, but that's even longer than だめだった so it's a no go, I'm guessing. Any advice?

Answer 1

You don't really have to do anything special- just put the final verb (adjective) in the past tense.

学校まで走らなければならない - I have to run to school
学校まで走らなければならなかった - I had to run to school

This works with all three of the constructions you mentioned.

ならない = ならなかった
だめ(だ) = だめだった
いけない = いけなかった

Of these, I see ならなかった the most by far, but the other two are possible.

Your suggestion of 「いけないだった」 is not possible, because it is ungrammatical. The past tense of an i-adjective is -かった; you can't append -だった. So it should instead be 「いけなかった」.