[R] how to make some characters in the xlab of a plot to be superscripted or subscript?

[Jing Yang]

Dear R-users,

I am trying to make my plot nicer. Does anyboby know how to make some characters in the xlab of a plot to be superscripted or subscript? ?
for example "m3/s" in the x-axis label, how to make 3 supersripted?

Best,Jing