用大坝阻断河流使得鱼类无法逆流而上去产卵，同时淤泥无法顺流而下去肥沃土地。
Blocking a river with a dam also blocks the movement of fish upstream to spawn and the movement of silt downstream to fertilise fields.
每年鲑鱼卵都会在哥伦比亚河中孵化，小鲑鱼顺流而下进入太平洋，等到成熟后又会逆流而上抚育下一代。
Salmon hatch in its waters, migrate downstream to the Pacific Ocean, and return against the current to breed.
利用顺流及逆流网络方程提出一种确定电源与负荷功率分配关系的功率分解解析方法。
This paper proposes an efficient analytical method for power allocation, which makes sure of the power transferred between generators and loads using downstream and upstream network equations.
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