题目

With rural ecosystem improving, the number of tourists to villages ________ year by year. A . have increased B . increases C . is increasing D . are increasing 答案：C如图所示，平行金属板中带电质点P处于静止状态，不考虑电流表和电压表对电路的影响，当滑动变阻器R4的滑片向b端移动时，则                （    ）A．电压表读数减小       B．电流表读数减小C．质点P将向上运动     D．R3上消耗的功率增大