He is the only one of the students who _____ a winner of scholarship for three years.

A．is

B．are

C．have been

D．has been

在直流电路中，电容器串联时，各电容器上的电荷量分配与其电容值（）

A、成正比

B、成反比

C、无关

D、与之平方成正比