—Of all your coats, why do you like this one best?

—Because it’s _________ than the others.

A．much beautiful.

B．more expensive.

C．much cheap.

D．much more beautiful.

电源电动势在数值上等于（）。

A、电源端电压

B、电源开路电压

C、负载两端电压

D、电源内压降