Saber and caber are irregular in El Pretérito Indefinido but both follow the same pattern:
| |
saber (to know) |
caber (to fit) |
| yo |
supe |
cupe |
| tú |
supiste |
cupiste |
| él / ella / Ud. |
supo |
cupo |
| nosotros / nosotras |
supimos |
cupimos |
| vosotros / vosotras |
supisteis |
cupisteis |
| ellos / ellas / Uds. |
supieron |
cupieron |
Here are some examples to read and listen to:
No supe que decir.I didn't know what to say.
Tú no supiste la verdad hasta dos años después.You did not learn the truth until two years later.
La maleta no cupo en el coche.The suitcase did not fit in the car.
Nosotros cupimos bien en el avión.We fitted in the plane comfortably.
Vosotras supisteis los resultados muy pronto.You found out the results very soon.
Los muebles cupieron en la casa.The furniture fitted in the house.
Caber and saber belong to a group of verbs that all have an irregular stem but share the same set of endings. To learn more about this have a look at
Irregulares en Indefinido/mismas terminaciones.
La maleta no cupo en el coche.The suitcase did not fit in the car. Vosotras supisteis los resultados muy pronto.You found out the results very soon. Los muebles cupieron en la casa.The furniture fitted in the house. Nosotros cupimos bien en el avión.We fitted in the plane comfortably. No supe que decir.I didn't know what to say. Tú no supiste la verdad hasta dos años después.You did not learn the truth until two years later. 
