adj.上游的；逆流而上的
adv.向上游；逆流地
This is the upstream part of the lake. 这里是湖的上游。
A water vole swam vigorously upstream. 一只水鼠奋力向上游游去。
The salmons are running upstream. 鲑鱼正在向上游洄游。
We paddled the canoe slowly upstream. 我们慢慢地划着独木舟逆流而上。
