题目内容：

 

About one dozen ancient bridges were still buried under the earth       1.________

in Beijing, according to Kong Qingpu, an expert in the bridge field.      2.________

The 13 bridges were built during the Yuan, Ming and Qing dynasty      3.________

and they were buried under the earth main for two reasons. Firstly,       4.________

some open rivers were changed into covering pipes and their bridges     5.________

were buried, too. Secondly, some open rivers were filled. Neither were    6.________

their bridges. Kong who has worked a specialist for 47 years wants       7.________

to be record the underground bridges. He tries to make a list of them and   8.________

add them to the history of bridges. Ancient bridges, both above or        9.________

under the ground, are all paid attention to. We must be protected.        10.________