[经] ratio of operating expenses to sales

yíng yè fèi yòng yǔ xiāo huò bǐ lǜ ㄧㄥˊ ㄧㄝˋ ㄈㄟˋ ㄩㄥˋ ㄩˇ ㄒㄧㄠ ㄏㄨㄛˋ ㄅㄧˇ lv4