巨石阵，几千年前怎么搬的？

Stonehenge sits on a plain in England. 巨石阵在英国的一片平原上。 It was built thousands of years ago. 它是几千年前建好的。 Its stones weigh many tons each. 每块巨石都有几十吨重。 No one knows how people moved them. 没人知道古人是怎么搬动它们的。 No one knows how they stood them up. 也没人知道他们是怎么立起来的。 The truth is still a big mystery. 答案至今还是个谜。