"It was miserable."
Translation:Roedd hi'n ddiflas.
I typed Oedd hi'n ddiflas. which is what I (thought I) had learned in another course, but was marked "almost correct".
Is it wrong? Too colloquial?
(For "I was", I learned "o'n i", by the way - is that accepted or do I have to use "Roeddwn i" or something like that on Duolingo?)
Oedd hi'n ddflas? and O'n i...?/Oeddwn i...? are question forms.
Roedd hi'n ddiflas and Ro'n i.../Roeddwn i... are the usual forms for positive statements.
They should be explained somewhere in the course notes, or in various internet sources and in basic books on the language. Look up bod on www.gweiadur.com to see a full conjugation table.
I had a look in my grammar book (Gareth King) and found (§239) that he lists the "o'n i; oedd e/hi" etc. forms for positive statements as well in the spoken language, which has simplified the system that is "much favoured in textbooks for its neatness". (So I wasn't imagining things when I thought I had heart those in SSiW, which focuses on spoken language.) And that there is this "in this system ... no difference between AFF[irmative forms] and INT[errogative forms] except for intonation".
I'll try to keep in mind that Duolingo expects the textbook (written) forms with r- for positive statements, rather than the simplified colloquial/spoken form.
Thanks again for your answer!