上水道

一般人都知道上水道和下水道是什么，但是中水道是什么呢？

Most people know about water sysytem ( up water ) and sewer ( down water ) system , but what is a middle water system ?

流水在冰面上开凿出条条水道

The spill water then carves its way through the ice .

向上变细的水道可以出现在好多种环境中，从海底峡谷到冲积扇。

Upward-fining channels may occur in a wide range of environments , from submarine canyon to alluvial fan .

巴拿马运河不仅是地球上最重要的水道之一，也是令人叹为观止的自然奇迹。

Not only is the Panama Canal one of the most important waterways on Earth , it 's also a site of incredible natural wonders .

听起来挺大的，但冰冠的水还不足以覆盖火星上所有地方的水道和侵蚀地貌。

It may sound large , but doesn 't contain nearly enough water to account for the flood channels and other erosion features that appear all over the place on Mars .

广州处于南海之滨三江总汇之地，历史上水网密布，水道纵横，城市的发展变化一直与城市水系的演变息息相关。

Guangzhou , located in South China Sea coast , is the confluence of three rivers . With dense water network and staggered waterways , the development of Guangzhou has been closely related to the evolution of the urban water system .