如图所示，电源电压不变，R₁为定值电阻，R₂为滑动变阻器。当开关闭合后，滑片P向右移时，下列说法中正确的是

A．v1的示数变大

B．v2的示数变大

C．A的示数变小

D．v1和A的比值不变

I can't understand why he ________ so selfish. He isn't usually like that.

A．was

B．had been

C．is

D．is being