Correction こにちは→こんにちは 危ない　は　きけん　緒名島すか→「危ない」　は　「きけん」　と　おなじですか ありがとございます→ありがとうございます→よろしくおねがいします。I hope you will take care of me.＝Thanking you in advance. To say ありがとう（ございます） is strange because you haven't known whether someone gives you a favor. It might be a correct expression in English. But in Japanese, we don't say "ありがとう（ございます） Thank you" before we know someone gives us a favor. Answer 危ない is a native Japanese word. It is an usual word. 危険だ／な is a loan word from Chinese language. It is a stiff word.

http://ameblo.jp/thai-koi/entry-11931737770.html This is one theory, I don't know if you can read this? Please tell me if you can't. I am also going to look for more answers :)