Mysister usually thinks in her own language first ,then she turns her words into English.

问题描述:

Mysister usually thinks in her own language first ,then she turns her words into English.
.为什么用介词in?【答案是in..】

这里介词in是表示方式或手段,即用她自己的语言,这是介词in的用法之一,如:
He can tell the story in English.可是网上有人说是by ,说是by one‘s own不用by,by常用来表示手段,或用于交通工具方面,如:He goes to school by bus.