c -> zc if the conjugation adds an 'a' or an 'o' to the stem; some c -> j changes in the subjunctive

aducir - to adduce, to bring forward in argument, to cite as pertinent or conclusive

deducir - to deduce
inducir - to induce
introducir - to introduce
producir - to produce
reducir - to reduce
traducir - to translate
comenzar - to start, to begin
empezar - to begin, to start

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