"기본적인 이론은 일반적으로 같습니다."
Translation:The basic theories are generally the same.
Shouldn't there be a 들 at the end of 이론? Because it's "theories" instead of "theory?"
It's usually only used for people and animals, so 이론 can mean both "theory" or "theories".
What does -적 mean? It's the suffix for both the words basic and general.