"只有你一个人吗?"用英语怎么说?

一般来说是不会用alone,准确点可以是:
Is it only you here?
Are you the only one here?
You are the only one here, aren't you?

Just by yourself?

如果是在口语里，我会说 You are alone?用升调

也许是 Are you alone？吧

Only you stay here?