“掌握思想教育，是团结全党进行伟大政治斗争的中心环节”，这就是说，中 * * 党建设中最主要的问题是

A．着重思想上建党

B．整风形式

C．实行三大优良传统与作风

D．坚持民主集中制原则

My father was preparing for his speech __ my mother was doing some washing last night.

A．if

B．while

C．unless

D．until