一水箱，容积是120升，这个水箱长是10分米，高0.2米，宽是[ ]

A．0.6米    

B．60米   

C．600米

--- You don’t seem to enjoy your meal very much.

----- Not really, I’m just______.

A．on diets

B．on a diet

C．on the diet

D．in a diet