题干
The pilot asked all the passengers on board to remain _________ as the plane was making a landing.
A：seat
B：seating
C：seated
D：to be seating
答案(点此获取答案解析）
C
、极板面积为S，电容为
，其中
是常量。对此电容器充电后断开电源。当增加两板间距时，www.ks5u.com电容器极板间
的输电线输电给940km外的用户，其输出电功率是3×106kW。现用500kV电压输电，则下列说法正确的是