A Human being is a soft, weak creature. It needs constant supplies of air, water, and food; it has to spend a third of its life asleep, and i can't work if the temperature is too hot or too cold, But a robot is made of strong metal. It uses electrical energy directly, near sleeps, and can work in any timperature. It is stronger, more efficient-and some times more human than human beings. Issa Asimov was one of the greatest science-fiction writers, and there short stories give us an unforgettable and territying vision of the future