causal features of preposoitions по and из-зa in russian language

causal prepositions по and из-зa in russian language are used for theexpression of undesirable or inconvenient facts and conditions and carrynegative charge and connotation. however, their usage requires differentgrammatical structures. moreover, they are used with different nouns.therefore, the sublties invovlved in some similar cases of the usage of theseprepositions for the expression of cause means, more often than not, difficultyfor iranian students while speaking russian as well as in translating russiantexts. the causal features of these prepositions have not unfortunately beeninvestigated thoroughly enough. in this regard, the present article aims toaddress, in adequate details, the functional and usage differences andsimilarities of these two causal prepositions, по and из-зa, in russian languageand their equivalents in persian language, in order to move toward theelimination of this problem and to be of practical help for translators throughoffering correct or more suitable equivalents in the translation of persian textsinto russian and vice versa.