A.so far as
= as far as
as far as就...而言,至于,远到
As far as I am concerned,I'm not against your plan.
就我而言,我并不反对你的计划.
B.as long as 只要
例：I don't mind as long as it doesn't rain.
只要不下雨就行了
so far as和 as long as 二者都有“只要.”的意思,但
so far as还有“在.范围内,到.为止”的意思；而
so long as还有“假如,既然”的意思.
并非都可以互换的!
C.as soon as一……就……
例：I'll write you as soon as I get there.
我一到那儿,就给你写信因此,应该选B,句意为：假如他们支持他,他就不必退出了.