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pitch black
夏の間に肌がまっ黒に焼けた。
My skin got deeply tanned over the summer.
煙突の中はまっ黒で何も見えなかった。
It was pitch black inside the chimney and I couldn't see anything.
泥遊びをして服がまっ黒になった。
My clothes turned black from playing in the mud.