短語(yǔ)詞組短語(yǔ)a navigaBle river 可通航的河流non -navigable river 不通航河流re -navigable river 復(fù)航河流Navigable river reach 通航段Un -navigable river reach 斷航段navigable river in mountainous region 山區(qū)通航河流 返回 navigable river