1、as far as 指物理上的距离
as far as 属于常见的 as …as 句型，表示同级的比较，意为”和…一样远，远至“等，指物理上的距离，此时的 as 可以是介词，也可以是连词，例如：
We didn't go as far as the others.
我们不如其他人走得远。
2、as far as 指抽象上的程度
当 as far as 指抽象上的程度时， as far as 相当于一个从属连词，置于句首时，用逗号与后面的主句分开。
1）as far as I (can) know/see/remember意为“就我所知；尽我所记得的；
As far as I can see, you've done nothing wrong.
依我看，你没有做错任何事。
They returned at nine as far as we know.
据我们所知，他们九点回来。
2）as far as it goes，意为“在一定程度上”，通常指不足，例如：
It's a good job as far as it goes, but it may need more work.
就目前而言，这是一份好工作，但可能还需要更多的工作。
3）as far as possible，意为“尽可能，尽量”，相当于 as much as possible，例如：
Plan your route in advance, using main roads as far as possible.
预先安排好你的路线，尽量走大路。
