Stem-Changing verbs (u….ue)
The irregular verbs change their stem in all the forms except for nosotros/as/we and vosotros/as/you forms. Additionally, remember that it is always the last vowel in the stem (what is left after you remove the infinitive marker (-ar-er-ir) that has a vowel change.
There is only one Spanish verb that has the change u —> ue. That verb is jugar that means to play (a game), this is whey it is important just to remember it.
Jugar/To play (any game)
|(yo)||jueg o||I play, I am playing, I do play|
|(tu)||jueg as||you (fam. sg.) play, you are playing, you do play|
|(el, ella, Ud.)||jueg a||he, she, you (pol. pi.) play(s), he, she, you is/are playing,|
|he, she, you does/do play|
|(nosotros/-as)||jug amos||we play, we are playing, we do play|
|(vosotros/-as)||jug ais||you (fam. pi.) play, you are playing, you do play|
|(ellos/-as, Uds.)||jueg an||they, you (pol. pi.) play, they, you are playing, they, you|