- She's the only person WHO can speak seven languages. or - She's the only person TO speak seven languages. - She's the first person WHO can speak seven languages. - She's the first person TO speak seven languages. The only / the first / the second / the next / the last (etc.) + to ...

@cowboy, "she is the only first person WHO" is incorrect. You can't combine "only first" like that.* Pick one of three, like: "She's the only person ever to have graduated from Harvard at age 7." Or, "She's the first person ever to graduate from Harvard at age 7." Or, if need be, "She's the first AND only person ever to have graduated from Harvard at age 7." So, in the topic starter's example, if you wanted to use both 'first' and 'only', you'd say something like: "She is the first and only person who can speak seven languages." -- * Only in special cases you can, where it means something else, like: "Only first and last name, please."

I'm still confused after seeing all the answers, i just want to know whether we use "Who"or "That" in the sentence like"she is the only person WHO can speak English".

@Mark Kramer o.k no problem amigo!! cowboy...

@cowboy, while "She is the only and first person" is not grammatically wrong, "first and only" is simply the idiom you would be using here. As for the order of 'first' and 'only,' that's the nasty things about idioms: they don't generally come with a manual. :) You basically just have to memorize them.