一回生二回熟
yī​huí​shēng'èr​huí​shú

strangers at first but friends later

  1. 一 yī numeral
    one
    one; the number 1; single; alone
  2. 回 huí measure word
    [times]
    (measure word) the number of occurrences of an event or action
  3. 生 shēng nounadjective
    unfamiliar
    unfamiliar; strange; unacquainted
  4. 二 èr numeral
    two
    the number two; 2
  5. 回 huí measure word
    [times]
    (measure word) the number of occurrences of an event or action
  6. 熟 shú adjective
    familiar
    familiar; well-acquainted; well-known through frequent contact