on the hour

例句：

1. Father must take his pill on the hour.
   父親必須在每點鐘準點吃藥丸。
2. On July third; every hour on the hour.
   在七月三日這一天; 時時刻刻
3. He arrived on the hour.
   他準時到達。
4. The London bus departs every hour on the hour.
   倫敦的公共汽車每小時零分開出一趟。