电磁波与机械波相比较(　　)．

A．电磁波传播不需要介质，机械波传播需要介质

B．电磁波在任何介质中传播速度都相同，机械波的速度大小取决于介质

C．机械波有横波、纵波，而电磁波只有横波

D．机械波和电磁波都具有一切波的特性

My father feels ________ because he heard from ________ today.

A．happy；an old friend of he

B．happy；an old friend of his

C．happily；one of his old friends

D．happily；an old friend of him