press ▁would ▁be . ▁Lady ▁Z hen ▁was ▁his ▁wife . ▁C ao ▁Pi ▁sum mon ed ▁Lady ▁Z hen ▁to ▁Lu oy ang , ▁but ▁Lady ▁Z hen ▁refused ▁because ▁of ▁her ▁poor ▁health . ▁In ▁ 2 2 1 ▁Lady ▁Z hen ▁died ▁and ▁the ▁position ▁of ▁em press ▁went ▁to ▁Gu o ▁N ü w ang . ▁ ▁Gu o ▁N ü w ang ▁did ▁not ▁bear ▁C ao ▁Pi ▁any ▁children . ▁C ao ▁R ui ▁was ▁the ▁el dest ▁of ▁C ao ▁Pi ' s ▁sons , ▁but ▁because ▁of ▁his ▁mother ' s ▁death , ▁he ▁was ▁not ▁inst ated ▁as ▁the ▁crown ▁prince . ▁Instead , ▁C ao ▁R ui ▁was ▁appointed ▁" Pr ince ▁of ▁P ing y uan " ▁after ▁his ▁father ' s ▁asc ension ▁to ▁the ▁throne . ▁C ao ▁Pi ▁did ▁not ▁appear ▁to ▁have ▁seriously ▁considered ▁any ▁other ▁son ▁as ▁he ir . ▁( It ▁might ▁have ▁been ▁because ▁the ▁other ▁sons ▁were ▁all ▁significantly ▁younger , ▁although ▁their ▁ages ▁were ▁not ▁recorded ▁in ▁history .) ▁In ▁the ▁summer ▁of ▁ 2 2 6 , ▁when ▁C ao ▁Pi ▁was ▁seriously ▁ill , ▁he ▁finally ▁named ▁C ao ▁R ui ▁as ▁his ▁crown ▁prince . ▁On ▁his ▁death bed , ▁he ▁entr usted ▁C ao ▁R ui ▁to ▁the ▁care ▁of ▁C ao ▁Z hen , ▁Chen ▁Q un ▁and ▁S ima ▁Y i . ▁Following ▁his ▁father ' s ▁death , ▁C ao ▁R ui ▁asc ended ▁the ▁throne