--I left my handbag on the train, but luckily someone gave it to a railway official.

--How unbelievable to get it back! I mean, someone           it.

A．will have stolen

B．might have stolen

C．should have stolen

D．must have stolen

如图实线为电场线，虚线为某离子只在电场力作用下的运动轨迹，已知离子由A点向B点运动，则下边说法正确的是( )

A．离子带负电

B．离子A点的速度小于B点速度

C．离子在A点的加速度大于B点加速度

D．A点电势能大于B点电势能