"给某人照相"用英语可以说 "take a photo of someone"。这个短语来源于英语中常用的 "take a photo"（照相），加上一个定语 "of someone"（指某人），就可以指定是某个人的照片了。

例句：

Could you please take a photo of me and my friends?（你能帮我照张合照吗？）

I took a photo of her when she wasn't looking.（她没看着我时，我给她照了张照。）

The photographer asked me to take a photo of the sunset.（摄影师要我给日落拍张照。）