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


I learned it from [this
guide](http://www.guidetojapanese.org/learn/grammar/must), 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?




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」.

