用英语说say()English用钢笔写write()a pen

say in english
write with a pen

Say in English 语言都是用in这个介词, say in Chinese,Say in German...但是speak后面直接加语言种类 比如speak English.
write with a pen用钢笔写字。再如paint with a brush,with在这里都有"用"的意思。

用英语说：speak in English,say sth. in E
用钢笔写：write with a pen

with

in
with