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。

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.

youdao

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。

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.

youdao