When the one chair in the room was at its usual place before the table, the canal was unnavigable.
若是屋里唯一的椅子放在了桌前平常的地点，“运河”航行就会受阻。
2
By 1700 the Virginia frontier had been pushed as far west as the fall line-the point upstream at which the rivers emptying into the Atlantic became unnavigable.
到了1700年，弗吉尼亚州的边境已经向西远推到了瀑布线——上游河流倾泻于大西洋从而不能通航的点。
3
Corporate websites: I recently co-judged a competition of nominated best-of-class business websites, and I was aghast at how unnavigable and useless most of them were.