upstream line的意思|示意

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。

This digitalized optical fiber transmission system is upstream line of the bi-directional optical fiber transmission system.

数字化光纤传输系统，为有线制导光纤传输系统的一个部分；

Control supply line water pressure. install a soft seated spring loaded check valve upstream of the assembly.

控制供应管道的水压。在总成的上游安装一个软阀座，弹簧负载止回阀。