so／as far as
1．to the place mentioned到达某个提及的地方
He walked as far as the post office．他一直走到邮局。
2．the same distance as象…一样远
We didn't go so far as the others （did）．我们走得没有其他人那么远。
3． to the extent that在…范围内；就…而言
So far as I know he will be away for three months．就我所知，他要外出3个月。
The experiment is going on smoothly，so far as I know．据我所知，实验正在顺利进行。