Rather than think of 'nida' as "to be verb", realize that every verb and every adjective ends in da (다) in dictionary form. For verbs, you might think of it like the word "to" which is used to form the infinitive of English words--to go, to write, to live etc. 니다 is somewhat like a conjugation would be in other languages, although in Korean it doesn't have anything to do with case or person, but is a matter of formality. All Korean sentences end with an adjective or a verb, and the ending of that adjective or verb can change based on the status of who one is talking to or talking about. Both 이다 and 있다 are translated "to be", but strange as it seems to English speakers, Korean grammar experts do not classify either as verbs. (동사). It seems natural to think of them as verbs, so I continue to do so, however one shouldn't necessarily correlate the 이다 honorific speech ending with the 이다 verb (or whatever it is called.)
Actually the past tense of 나빠요 /nappayo/ is 나빴어요 /nappasseoyo/. And the past tense of 나쁩니다 /nappumnida/ is 나빴습니다 /nappassumnida/. They are different politeness levels so they don't automatically get conjugated the same in the past tense. Anything that ends with an -읍니다 is going to be the most polite or formal.
In Korean, many sounds really have 2 or more different pronunciations to the English speakers' ears. For instance, in this case, you hear /m/ in the place of something where you believe /b/ should be heard. This is because the mouth and lips when you make these sounds (which is called the place of articulation) are in the same place. Your lips are closed and your tongue is in the same position inside your mouth. They are both voiced bilabial plosives. The only difference is when you make the /b/ sound, air travels outwards of your mouth, and when you make the /m/ sound the air travels through your nose, making it a nasal. You hear it all the time in Korean. Like the word for radish, 무 /mu/; it is pronounced as /부/ or /bu/ all the time by Koreans. It's something you just have to get used to. It goes for many characters. Alot of listening practice.
Yes! Because /n/ and /d/ also share a place of articulation, but /n/ is nasal and /d/ is oral. Yeah I hear that too plus I hear /doona/ for 누나 /noona/ alot. I've observed alot of times Koreans aspirate their consonants- meaning they add an extra puff of air to a normally airless or less airy consonant when speaking, especially at the beginning of a word. My boyfriend is Korean and I've asked him about this, and he didn't realize the difference in sound until I had him pronounce it normally, then the way it's spelled. I'm a linguist so I have a trained ear, but watching Korean tv shows and movies helps me with listening more than anything else.
Please do not forget, it was only a few people who wanted to do very wrong. Many people stepped up to the challenge and became heros. But, Romans 3: 23-24 in the Holy Bible states: "All have sinned and fall short of the glory of God, being justified by His grace through the redemption of Christ Jesus" .-_-
I will try translating into Korean. Any mentoring is more than welcome...(-;
제발 잊지 마세요, 아주 잘못하고 싶었던 사람은 소수에 지나지 않았습니다. 많은 사람들이 도전에 나서고 영웅이되었습니다. 그러나 로마서 3 장 23 ~ 24 절에는 성서에 "모든 사람이 죄를 지 었으며 하나님의 영광에 이르지 못하고 그리스도 예수 안에있는 구속을 통해 하나님의 은혜로 말미암아 자유롭게 의롭다 하심을 얻었 느니라"고 읽었습니다. -_-