upstream
adverb, adjective [ before noun ] uk/ˌʌpˈstriːm/ us/ˌʌpˈstriːm/
在上游（地）;向上游（地）;逆流（地）
(moving) on a river or stream towards its origin
Salmon swim upstream against very strong currents to reach their breeding areas. 大麻哈鱼会迎着湍急的水流游向上游它们的产卵区。
在（某过程或事件的）前阶段
relating to an earlier stage in a process or series of events
The company's upstream business includes oil exploration and production. 这家公司的上游业务包括石油勘探和开采。
Opposite: downstream