过去完成时的被动语态常用于以下情况：

(1)表示过去某一时间以前已经完成的动作，常与by,before等引导的时间状语连用。

Bythetimehegottotheschool,thefirstperiodhadbeenfinished.

Theclassroomhadn'tbeencleanedbeforetheteachercame.

Howmanybuildingshadbeendestroyedwhenthehurricaneended?

Hadthenewplanbeendiscussedbeforethemeeting?

(2)在told,said,knew,heard,thought等动词之后的宾语从句中，若表示过去某一被动动作时，用过去完成时。

Thesaidtheproductioncostshadbeenreduced.

Theboywasremindedthathishomeworkhadnotbeenhandedin.

Themediareportedmorethan1,000peoplehadbeenkilledintheearthquake.

(3)根据语意可以判断出动作先后的被动语态，用过去完成时。

Astheassignmenthadbeendone,hewentontosearchtheInternet.

Hedidwhathehadbeentoldto

另：当从句由after，before，when或assoonas引导时，主句和从句都可以用一般过去时。

Whenhearrived,hecalledher.

Theylockedthedoorbeforetheyleft.