“Is it just you?”

This is a common way of asking if someone is alone or if they have any companions with them. It is a popte and straightforward way of inquiring about someone's situation.

Example:

A: Hey, how's it going?
B: It's going great! Is it just you today or do you have company?

Translated to Chinese:

A：嘿，怎么样？
B：非常好！今天只有你一个人吗，还是有人陪着你？