Quasiary predicates are partial predicates over partial states (partial assignments) of variables. Such predicates do not have a fixed arity. They are used to represent program conditions and requirements, therefore logics of quasiary predicates are programoriented logics. Classical predicate logic is based on total n-ary predicates. We demonstrate how classical logic can be represented as logic of quasiary predicates. Properties of such representation are investigated. Obtained results can be used for program verification.