根据短文内容和所给汉语提示，写出短文空白处各单词的正确形式,每空限填一词。

My friend Nancy is   1 (15) years old. She is a clever girl in my class. She comes from  2 (日本).But she likes China very much. Now she  3  (居住) in Shanghai with her parents. Her house is not in the   4 (中心)of the city but she enjoys it. There  5 ( 有 )a river through her neighborhood.  6 (在对面) from her building is an old park.  7 (如果) she is tired, she can   8 (散步 ) in it to relax herself. She says she wants to be a   9 (女警察) though sometimes it is kind of  10 (危险的)

在河流上修建拦河坝时，为了保证航道的畅通，人们修筑了船闸，这是利用了   的原理。