—Susan, why are you still here? They arc all ready to start.           .

—I'm sorry.  but I             when to start[ ]

A. was told      

B. told          

C. tell        

D. wasn't told

常温下，金属具有导电性，但部分非金属也能导电．例如（　　）

A．硫

B．石墨

C．红磷

D．金刚石