I have a history class at 9 o'clock.
我9點鐘有歷史課。
We arrived at two o'clock and left at ten past.
我們兩點鐘到達，十分鐘后離開。
I have to collect the children from school at 3 o'clock.
我得在3點鐘到學校接孩子。
By my watch it is two o'clock.
我的表是兩點鐘。
At the first stroke it will be 9 o'clock exactly.
等到鐘敲第一下時就是9點整。