[经] cost of the oldest stock method
zuì chén jiù cún huò chéng běn fǎ ㄗㄨㄟˋ ㄔㄣˊ ㄐㄧㄡˋ ㄘㄨㄣˊ ㄏㄨㄛˋ ㄔㄥˊ ㄅㄣˇ ㄈㄚˇ