In order to improve English listening, _______.

A．he bought a Walkman

B．his father bought him a Walkman

C．a Walkman was bought by him

D．a Walkman was offered to him

国家民委（1980）民文字第432号文件批复：二、同意八省区蒙古语文用书出版协作小组划归八省蒙古语文协作小组管理。今后八省区蒙古语文教材和图书均由（）承担供应。