In his paper [1] Chang provides among other things answers to questions of the following type: Given two models and of powers α and β, respectively, what is the least λ such that implies His proofs are by induction on the quantifier rank of formulas and they use an idea which in the case of ordinary first-order language goes back to Ehrenfeucht and Fraïssé. But, as we show, one can easily prove that if λ is big compared with κ and with the cardinality of the universe of the structure , then every L∞κ-formula is equivalent modulo the set of all Lλκ-sentences which hold in to a Lλκ-formula. From this, Chang's results follow immediately. The same method can be applied to similar problems concerning generalized languages.