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 it 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, never sleeps, and can work in any temperature. It is stronger, more efficient - and sometimes more human than human beings.

Isaac Asimov was one of the greatest science-fiction writers, and these short stories give us an unforgettable and terrifying vision of the future.

The Oxford bookworms library offers a wide range of original and adapted stories, both classic and modern, which take learners from elementary to advanced level through six carefully graded language stages:

Stage 1 (400 headwords)

Stage 2 (700 headwords)

Stage 3 (1000 headwords)

Stage 4 (1400 headwords)

Stage 5 (1800 headwords)

Stage 6 (2500 headwords)

This book is at stage 5.

At the end of this book, it supplies questions to help you check your comprehension after reading the story.