16.Have you ever been to the Great Wall of China?Originally (61)built (build) on the northern border of the country as a military defense project,it is the longest man-made structure throughout the world,(62)whose influence has been profound in the history of architecture.Due to the limitation of machinery at the time,it was constructed entirely by hand.(63)Dating (date) from as early as the Spring and Autumn and Warring States periods,the wall is now a national symbol and a popular tourist attraction.With a (64)length (long) of 6350kilometers,the Great Wall winds its way through mountainous regions and (65)looks (look) really magnificent.
There is no doubt that the Great Wall is a stunning legacy the whole world,not only China,has been left with.In fact,ancient China has also given the world many great (66)inventions (invent).To give an example,Su Song,an eleventh-century monk about (67)whomvery little is known,invented the first real clock.A man named Cai Lun was considered (68)to have made (make) paper from the bark of a tree in about 105AD,and this invention turned out immediately (69)successful (succeed).Printing was also invented in China as early as 868AD,and not until the year 1454AD (70)was the first book printed in Europe.