surface runoff[水文] 地表径流;地面迳流;地表径流量;表面径流
urban runoff城市径流
runoff coefficient流系数;经恋数
runoff generation[水文] 产流
river runoff河川径流;径流量;河流径流量
presidential runoff总统决胜选举
runoff cycle[水文] 径流循环;迳流循环
runoff change径流变化
N-COUNT（可数名词） A runoff is an extra vote or contest which is held in order to decide the winner of an election or competition, because no one has yet clearly won. 决选; 决胜赛 [usu sing, oft N 'between' pl-n]
There will be a runoff between these two candidates on December 9th.
在12月9日，将举行这两位候选人的决胜选举。