These verbs change or add a vowel to their stem, however they use the same personal endings as regular verbs. These changes occur in all personals form except nosotros and vosotros. For easy study we have classified them into groups.

*"Jugar" does not have an "o" but it changes just like the verbs in this group.

"Adquirir" does not have an "e" but it changes just like the verbs in this group.

All verbs ending in _uir (except those ending in _guir) are conjugated in the same way.

NOTE
In addition to these changes, there are also spelling changes, but the conjugations must preserve the infinitive sound. To learn this it is important to learn how the Spanish alphabet works.