根据句意及首字母（汉语）提示，补全单词。

1.  The l_    _  _ of the Yangtze River is about 6,300 kilometers.

2.  My house is about 120 square meters in s_   _   _ .

3. The giant panda feeds on b__     __.

4.  China is one of the oldest____      （文明）in the world.

5.  The Great Wall is known as a big man-made s_     ___.

关于北京市位置准确的说法是[ ]

A．华北平原北部

B．华北地区的东北部

C．濒临渤海

D．华北平原西南端