In L'Imparfait, almost all verbs conjugate in the same way, but verbs ending in -cer* require a slight spelling change to accomodate the soft c.
The letter ç ('c cedilla') is used in most cases except where an i can already keep the c sounding soft.
Example with lancer (to throw)
* Here are other -cer verbs which follow that pattern:
remplacer (to replace)
bercer (to rock)
annoncer (to announce)
Listen to some examples: