But could time travel actually be possible?Some scientists say yes,in theory.They propose using cracks in time and space called “wormholes”,which could be used as shortcuts to other periods.Einstein’s theory of relativity allows time travel in extreme circumstances.And British physicist Stephen Hawking says you could travel into the future with a really fast spaceship—going at nearly the speed of light.Though building such a spaceship would of course be no simple task.

　　Even if you could travel into the past,there is something called the “grandfather paradox”.It asks what would happen if a time traveler were to go back in time and have his own grandfather killed for some reason,and therefore prevent himself from being born.If the time traveler wasn’t born,how would he travel back in time?

　　And would you really like to visit the future?In H.G.Wells’ book,the main character travels into distant time where he arrives at a beach and is attacked by giant crabs.He then voyages 30 million years into the future where the only living thing is a black object with tentacles(触角).

　　If that’s what’s in store,maybe we are better just living in the present day after all.

　　(2016·北京海淀区期中考试)

　　1.The novel The Time Machine mentioned in Paragraph 2 aims to show . 

　　A.people’s interest in time travel

　　B.the special feature of the book

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