—Linda, I called you this morning, but nobody answered the phone.

—I’m sorry. I ________ football with my friends then.

A．play

B．played

C．am playing

D．was playing

岩石按形成的条件可分为：火山岩、沉积岩、变质岩三大类，大理石主要适用于室外，花岗岩主要适用于室内。