 The occupiers looted and destroyed much of Poland 's cultural and historical heritage , while persecuting and murdering members of the Polish cultural elite . Most Polish schools were closed , and those that remained open saw their curricula altered significantly . 
 The occupiers looted and destroyed much of Poland <a href='null_genetive' title='1'><mark>'s</mark></a>cultural and historical heritage , while persecuting and murdering members of the Polish cultural elite . Most Polish schools <a href='uninflect' title='2'><mark>were</mark></a> closed , and those <a href='null_relcl' title='3'><mark>that</mark></a>remained open saw their curricula altered significantly . 
The occupiers looted and destroyed much of Poland  cultural and historical heritage , while persecuting and murdering members of the Polish cultural elite . Most Polish schools was closed , and those remained open saw their curricula altered significantly .