"the river was navigable for 50 miles"
Those African leaders have now fallen victims of neocolonialism and sold their fellow Africans down the river.
那些非洲领袖现已沦为新殖民主义的牺牲品而将同胞出卖了。
And hast thou crost that unknown river, Life's dreary bound?
牛津高阶第八版
美国韦氏词典
Dictionary.com
Free Dictionary
维基百科 (自由的百科全书)