Verbos con cambio ortográfico g>gu (pretérito indefinido)

Stem-changing Spanish g>gu verbs in the simple past tense

Spanish verbs ending -gar have an irregularity when they are conjugated in the simple past in Spanish. 
The -g changes to -gu in the yo form, however the other forms are not affected.

For example:
jugar (to play) → yo jugué
pagar (to pay) → yo pagué
To see a list of verbs affected by this irregularity go to:
-gar Spanish verbs that change g > gu in the yo form in El Pretérito Indefinido



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