What is the correct past tense of 이다?
Is it 이었어요 or 였어요 or something else? If there one correct answer or does it depend on the context?
였다 follows a vowel, and 이었다 follows a consonant(batchim).
Examples:
그는 경찰이었다. (He was a policeman)
그는 아직 아기였다. (He was still a baby)
I believe 이었다 is the more 'correct' form, but they are both correct, one is just a shortened form of the other.
The same thing happens with 되었다 and 됐다