I've studied and speak three romance languages and for all of those there's a distinction between the "preterit tense" and "imperfect tense" where you say "I used to X." If you're saying you used to do something in Korean, is it still the same past tense conjugation or is there a different conjugation?
Ex. "I used to study Japanese" or "Every day I cooked dinner"
Thank you!
I don't think the sentence, "everyday I cooked dinner" is a grammatically correct sentence. The verb "cook" should be in present tense since you said "everyday", which is a regular habit or routine, in this occasion, it is only correct to use simple present tense.
I am not the expert but let me answer the example part you made.
I used to study Japanese" 나는 일본어 공부를 했었다./ 하곤 했었다./하곤 했다. either way seems ok
"Every day I cooked dinner" 나는 매일 요리를 했다. here you can just use simple past tense.



