[经] number of days sales in receivable

yīng shōu zhàng kuǎn de shōu kuǎn tiān shù ㄧㄥ ㄕㄡ ㄓㄤˋ ㄎㄨㄢˇ ㄉㄜ˙ ㄕㄡ ㄎㄨㄢˇ ㄊㄧㄢ ㄕㄨˋ