Verbs that add a -d
The verbs poner, salir, tener, valer and venir replace the vowel in the infinitive ending (-er/-ir) with a -d before adding the future endings -é, -ás, -á, -emos, -éis, án.
Verbs that lose a vowel
The verbs caber, haber, poder and saber lose the final -e in the infinitive ending (-er) before adding the endings for simple future.
Verbs with an irregular stem
The verbs decir and hacer change their stems before adding the simple future endings. The new stem is the same in all forms.
- Decir = dir-
- Hacer = har-