—________ does Lucy go to school every day?

—She walks to the bus stop, then takes the bus.

A．How far

B．How long

C．How often

D．How

跨导S在数值上等于阳极电压Ua为常数的条件下，栅极电压Ug微量变化所引起的阳极电流Ia的相应改变。（）对阳极电流的控制能力很强。

A.S越大，说明栅极电流

B.S越大，说明栅极电压

C.S越小，说明栅极电压

D.S越大，说明栅极电流