in 表示“用(某材料,原料或语言)”
with表示“用(某工具、手段)”
e.g. write in ink用墨水写
say it in English用英语说
write with a pen用钢笔写
see with eyes用眼睛看
举个例子说吧
I write it in English。是我用英语写
I write it with English。使我用English这个词写,全文都是English,Enlish,English
in ink是固定搭配,一般用with