Stem-changing Spanish c>zc verbs in the present subjunctiveIn Spanish some verbs ending in -cer/-cir undergo a stem change in the present subjunctive, in a very similar way they do in the present indicative. They will switch the -c for -zc. The difference is that while in the present indicative only the yo form is affected by this stem change, in the present subjunctive all forms keep the stem change.
Have a look at these tables showing both the present indicative and the present subjunctive of conocer (to know/meet):
él / ella / usted
|nosotros / nosotras||conocemos||conozcamos|
|vosotros / vosotras||conocéis||conozcáis|
|ellos / ellas/ ustedes||conocen||conozcan|