[经] amortization of premium on bonds purchased

goù rù zhài quàn yì jià de tān xiāo ㄍㄡˋ ㄖㄨˋ ㄓㄞˋ ㄑㄩㄢˋ ㄧˋ ㄐㄧㄚˋ ㄉㄜ˙ ㄊㄢ ㄒㄧㄠ