"여기는 날씨가 나빠요."
Translation:The weather is bad here.
Did you mean 'across language pairs' or is a 'Ross language pair' something I should know? Anyway please don't feel disheartened with tone of some of the feedback. It's just frustration. I'm personally delighted that here I am, a continent and a half away from Korea, able to learn the language at times that suit me, and for free when the academic option in town would cost me €hundreds. 고맙습니다. One day I will get to use what you've taught me in Korea!
Many verbs that end with ㅡ are irregular verbs. When a verb stem ends with ㅡ, you should ignore that, and instead look at the next-last vowel, and follow the rule out from that.
So 나쁘다 the next-last vowel is 아, so you add 아 to the stem. But when ㅡ and 아 merge, the ㅡ disappears, so it goes like:
나쁘다 --> 나쁘아요 --> 나빠요.
If there is no next-last vowel, or all vowels are ㅡ you add 어.
크다 --> 크어요 --> 커요
슬프다 --> 슬프어요 --> 슬퍼요.
I hope it makes sense!