as far as的意思是“就......而言（所知）”。
如：As far as I know, more than 10 million laid-off workers have found their new jobs.就我所知，一千多万下岗工人已经找到了新的工作。
as far as sth. is concerned是其中一种具体用法，意为“就某事而言”。
如：As far as the tourism of China is concerned, there is a long way to go.就中国的旅游业而言，需要做的工作还很多。
as long as意为“只要”，引导条件状语从句。
如：There is nothing that we can’t do so/as long as we keep on trying to do it.只要我们不断地努力去做，就没有什么事干不成。
