excite的副词是什么

　　There's a bus every hour on the hour.

　　每小时整点有一班公共汽车。

　　She was on the phone for an hour telling me her troubles.

　　她在电话上用了一个小时向我倾诉她的种种烦恼。

　　The bus goes past the building on the hour.

　　公共汽车在整点时经过这幢大楼。

　　There's a train every hour on the hour.

　　每小时整点有一班火车。

　　What does it mean if the bus leaves on the hour?

　　是什么意思如果总线上的树叶小时？