To express 'with, by means of' use Instrumental (with no preposition!).
— Почемџ онќ ничегћ не едїт?
"Why aren't they eating anything?"
— Потомџ что онќ не хотїт љсть такќми плохќми ножђми.
"Because they don't want to eat with such bad knives."
© 1981,1982,1991 by R.L.Leed, A.D.Nakhimovsky, A.S.Nakhimovsky
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