Como é que se diz isto em Chinês Tradicional (Taiwan)? 這裡 以 有什麼意思？ 怎麼用？

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It serves as a *particle functioning like "with" in English. I'd say usually you can replace it with 用, but 以 seems more formal to me. I'd use 以 in writing. Of course, I'm pretty sure there's going to be other uses with these two words, but don't worry about them now.
*Not sure if this is the right term linguistics-wise.

E.g.
我以平常心看待。 It is what it is. (Meaning I'll deal with whatever's thrown my way with peace of mind. This one's pretty hard for me to translate.)

以牙還牙。 An eye for an eye (牙 means tooth/teeth though).
This is a set phrase / idiom (成語), so you cannot replace it with 用.