_____ scores of times , but he still couldn’t understand it ．[ ]

A．Having explained              

B．Having been explained

C．Though it was explained        

D．It was explained

红十字会经费的主要来源为（）。

A.红十字会会员缴纳的会费

B.接受国内外组织和个人捐赠的款物

C.动产和不动产的收入

D.人民政府的拨款