No, adverbs don't play key roles in Korean any more than they do in other languages. Two crucial differences in sentence structure between Korean and English are: * word order. English has an S + V + O order, while Korean is in S + O + V. ex) I love you => 나는(S) 너를(O) 사랑한다(V). * particles. They mark a word's function, so Korean word order can be more flexible than in English. ex) For "I love you", you can say 너를 나는 사랑한다, or even 사랑한다, 나는 너를, if necessary. You can do a search on "Korean sentence structure". There are many sites that explain it in detail.