Dear native English speakers,
would you say all the sentences? Do they have the same meaning?
(a) Come back before it gets dark.
(b) Come back before it becomes dark.
(c) Come back before it is dark.
(d) Come back before dark.
You could say all of them, and they would have the same meaning, but I would say (a) is easily the most natural of all of them because "get dark/light" is the natural collocation.
Hi hirashin!
It should be clear who said this sentence, everything else would be illogical. The term "dark" is basically relative because it does not define a specific point in time. His mother could also say, "Come home when the street lights are off". That would probably be at 5:00 in the morning.