what (...) for?a) REASONused to ask why someone does something 为什么? ‘She’s decided to work part-time.’ ‘What for?’ “她决定去做兼职。”“为什么?”
What did you do that for? 你为什么那样做?
b) REASONused to ask what purpose or use something has 〔某物〕有何用处? What’s this gadget for? 这个小玩意儿是干什么用的?
what (...) for?• What's this tool for?