qiantang river is the biggest in zhejiang province, running from the west to hangzhou bay in the east. it serves as a river hinge, playing an important role in the water-transportation between the east and the west. it is encircled by a group of economically booming cities including shanghai, chinas leading industrial and commercial hub, and ningbo, one of chinas leading port cities. the extraordinary surging tide of the qiantang river is a world-renowned natural wonder caused by the gravitational pull of the stars and planets. the centrifugal force produced by the rotation of the earth and by the peculiar bottleneck shape of hangzhou bay makes it easy for the tide to come in, but difficult for it to ebb. the soaring tide of the qiantang river is such a marvelous spectacle that only the amazon rivers surging tide rivals it! annually, millions of people from both home and abroad flock there to watch the magnificent tide on the eighteenth day of the eighth lunar month (also around the mid-autumn day). when the surging tide comes, the water can rise up to a height of 30 feet and the noise it generates sounds like thunder, or thousands of horses running. various activities will also be held to celebrate the annual tide - watching festival, according to local custom. in terms of its history, the custom of watching the bore tide has happened for more than 2000 years. it first appeared during the first century. then, it became popular in the tang dynasty (about 7th -13th century). yangong town in haijing 45 km (about 28 miles) from hangzhou is the best place to watch the qiantang tide.
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（实习编辑：高奕飞）
