Question

stem changing verbs e - ie, sa
tu blank la paciencia en clase.
perder perdes pierdes pierde

Explanation:

In Spanish, the second - person singular "tú" form of the stem - changing verb "perder" (from E - IE) is "pierdes". "Perder" means "to lose", and the sentence "Tú pierdes la paciencia en clase" means "You lose your patience in class".

Answer:

pierdes