Being too confident like that is dangerous. Where in the world does that come from?
You could get hurt being too sure of yourself. How on earth did you become like this?
ーBeing too confident like that is dangerous. Where in the world does that come from?
「あんな風に自信がありすぎるのも危ないよね。一体どこからくるんだろう？」
to be confident で「自信を持つ」
dangerous で「危険な・危ない」
Where in the world のように疑問詞と使って「一体」を表現できます。
ーYou could get hurt being too sure of yourself. How on earth did you become like this?
「自信を持ちすぎると怪我をするよ。一体どうしてこんな風になったんだろう？」
to get hurt で「怪我をする」
to be sure of oneself で「自信を持つ」
How on earth のように疑問詞と使っても「一体」を表現できます。
ご参考まで！
カナダ 
