[经] depreciation-sum of expected life period method
yù jì nián xiàn zǒng shù zhé jiù fǎ ㄩˋ ㄐㄧˋ ㄋㄧㄢˊ ㄒㄧㄢˋ ㄗㄨㄥˇ ㄕㄨˋ ㄓㄜˊ ㄐㄧㄡˋ ㄈㄚˇ