-----Ken,         , but your TV is going too loud.

-----Oh, I’m sorry. I’ll turn it down right now.

A．I’d like to talk with you

B．I’m really tired of this

C．I hate to say this

D．I need your help

A、B两球质量相等，连接在质量可忽略的硬杆两端，硬杆可无摩擦绕O点转动，已知AO＜OB，在硬杆处于水平位置时，从静止释放，则在B球摆至最低点的过程中，下列叙述中正确的是（　　）

A．任何时刻两球的速度大小相等

B．杆对A球做负功，对B球做正功

C．杆对A球做正功，对B球做负功

D．两球组成的系统机械能守恒