as an occasion at once for joy and for fear; feel both joy and fear;in one way,it is a cause for joy,in another,a matter of concern ❍ 父母之年，不可不知也； ～。(《论语·里仁》) The years of parents may by no means not be kept in the memory,as an occasion at once for joy and for fear. ❍ 他们在这一形势面前，～。(《毛泽东选集》870) Faced with this situation it feels both joy and fear.