短語詞組短語canal river system 運河水系canal transport system 漕運制度canal distribution system 渠道分佈系統(tǒng)North Canal River System 北運河水系canal -system water use efficiency 渠系水利用系數open canal system 根部開放structures for canal system 渠系建築物canal safe transit system 運河安全通航系統(tǒng)canal system density 渠系密度 返回 canal system