adjective
BAD : Soon it began to become dark and it was time to go home.
GOOD : Soon it began to get dark and it was time to go home.
BAD : The last candle went out and everything became dark.
GOOD : The last candle went out and everything went dark.
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To refer to the time in the evening or at night when the daylight disappears, use get dark or (in formal styles) grow dark : 'In the winter it gets dark by five o'clock.' 'It began to grow dark and so we headed back to the shore.' To describe what happens when all the lights in a room, building, etc suddenly go out, use go dark or (especially in formal styles) be plunged into darkness : 'During the last storm the whole town was plunged into darkness.'