So basically, должна была is just a construction because there is no past form of должна, yes?
I opened the discussion button for the same reason geneven did. "I should have cooked soup" (my translation, which was accepted) means I did not do so, whereas "I had to cook the soup" means the chore of cooking the soup was assigned to me and I did it. That's a big difference in meaning! In one scenario there is soup, in another there isn't! It's hard for me to even believe that intonation would clear up the ambiguity. Isn't there a normal way to distinguish the two?
Thanks for making my comment clearer! Yes, with one translation there is soup and with the other translation there is no soup! Also, in writing there is no intonation, so it would not fix the ambiguity. Of course, English also has sentences that mean opposite things, so if that is true of the Russian, we of course must accept it.
It also accepted "I must have prepared soup." So there's soup, but I don't remember making it and I'm just guessing as to its origin.
I have an excellent resource whom I can ask about this, and I will get back to you. :)
Just because you had to cook soup doesnt mean you did, this sentence never reveals whether soup was cooked or not, rather just that it had to be done
Yes. The meaning can be conveyed with intonation: if it means "had to cook" then the word "должна" is stressed, if it means "should have" then it's either "приготовить" or "суп" depending on the meaning. Also, "Надо было приготовить суп" usually means "[I/you/he/she/they] should have cooked the soup".
"I ought to (должна) have made (была приготовить) soup." This shoule be acceptable to Duolingo surely?
Without this word ("я должна приготовить суп") this sentence would be in the Present Tense. This word is a mark of the Past tense here in this sentence.
OK, how to express need vs should vs have to? I feel this course is not very consistent in accepting these.
It depends on the context. You can translate these ones as "до́лжен / до́лжна / до́лжно", but there are two ways of the translation in Russian here:
1) "Я должен" "ты должен", "ты должна"
2) "Мне надо" , "ему надо", "ей надо"
There is no difference between these two choices
"You should" can be translated as "тебе́ сле́довало бы", then it will be a more polite form of the choices above.
"До́лжен" is masculine
"Должна́" is feminine
"Должно́" is neuter
"Должны́" is plural
sorry, I have a big problem with this. there is a huge difference between I should have made soup, and I had to make soup.
which one of these is the correct translation? this is a big deal actually.
"should have" is wrong. That refers to a requirement to do something in the past that was not done. It would require a conditional construction in Russian.
Готовит is imperfective and приготовит perfective. You can read more about it in the lesson Perfective 1.