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pitch black
日焼けして顔が真っ黒になってしまったよ。
I got sunburned and my face became completely black.
煙突の中は煤で真っ黒に汚れていた状態だった。
The inside of the chimney was blackened with soot.
停電で部屋が真っ黒になって何も見えなかった。
The power went out and the room became pitch black, I couldn't see anything.