There are only a few Spanish verbs that undergo these two changes in El Presente de Subjuntivo: o > ue and z > c
Almorzar (to have lunch) and forzar (to force) are two of these verbs.
Conjugating almorzar and forzar in El Presente de Subjuntivo in Spanish
to have lunch
|él / ella
|ellos / ellas
Notice how the -o- from the infinitive has changed to -ue- in all forms except for nosotros and vosotros.
And -z changes to -c in all forms (to preserve the original sound from the infinitive.)
Their endings are the same as other regular -ar verbs in El Presente de Subjuntivo.
Other derivatives of the verb forzar follow the same rule, for example:
esforzar = to strain
esforzarse = to make an effort
reforzar = to strengthen
See A2 Spanish verb list: Stem-changing verbs - present tense (o > ue) and Spanish expressions followed by El Subjuntivo
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