Nonequivalence
非等價, 反重合運算, “異”運算
??? 情景例句
that will bring parents and teachers together once a week
讓家長們及教師每星期一次
I get up before six o'clock every day.
每天我六點前起床。
He calls at every house in the street once a month and always asks for a meal and a glass of beer.
他每月對這條街上的每戶人家光顧一次，總是請求給他一頓飯和一杯啤酒。