Not only _______interested in Beijing Opera but ______beginning to show an interest in it.

A．the father himself is; all his children are

B．the father himself is; are all his children

C．is the father himself; are all his children

D．is the father himself; all his children are

一个人稳站在商店的自动扶梯的水平踏板上，随扶梯向上加速运动，如图所示，则 （   ）

A．人对踏板的压力大小等于人受到的重力大小

B．人只受到重力和踏板的支持力作用

C．人受到的力的合力对人所做的功等于人的重力势能和动能的增加量

D．踏板对人做的功等于人的机械能的增加量