MASCULINE FEMININE NEUTER SINGULAR NOM. efficax efficax efficax GEN. efficacis efficacis efficacis DAT. efficaci efficaci efficaci ACC. efficacem efficacem efficax ABL. efficaci efficaci efficaci PLURAL NOM. efficaces efficaces efficacia GEN. efficacium efficacium efficacium DAT. efficacibus efficacibus efficacibus ACC. efficaces efficaces efficacia ABL. efficacibus efficacibus efficacibus