A common verb that ends in -zar is comenzar. It is a stem-changing verb.
Do you know the yo form of comenzar in the simple present tense? It’s comienzo. Let’s follow the steps we have learned to conjugate this verb!
If we get rid of the -o in comienzo, we are left with comienz. Now, remember that verbs that end in -zar change z to c, so we have comienc.
Let’s use the present subjunctive endings for verbs that end in -ar to conjugate this verb: -e, -es, -e, -emos, -éis, -en.