Stem changing verbs PS

Stem changing verbs (-er/-ir) in the Presente Simple tense.
Verbos:
-er:
entender (to understand), querer (to want), perder (to lose), poder (to be able to), creer (to believe), tener (to have)
-ir:
dormir (to sleep), morir (to die), preferir (to prefer)

e-ie
o-ue