I can hardly imagine a hard-working man like Jacky Chan. Could you tell us ________?

A．how much time did he devote to charity

B．what is Jacky Chan like

C．if or not his new movie Police Story 2013 is shown

D．what makes him so energetic

钢轨探伤仪37°探头探测螺孔中心水平裂纹时荧光屏回波位置（）。

A、在螺孔波之前

B、在螺孔波之后

C、与螺孔波在同一位置

D、与螺孔波位置关系不确定