It is+时间段+since+时间点那It's 9 o'clock 是时间段还是时间点

It is+时间段+since+时间点那It's 9 o'clock 是时间段还是时间点
It is+时间段+since+时间点
那It's 9 o'clock 是时间段还是时间点

It is+时间段+since+时间点那It's 9 o'clock 是时间段还是时间点
可作为起始或结束参考点的时间或事件都视为时间点,九点钟当然是时间点.

时间点

比较下列句子；1 The work began at 9 o'clock.可改写为 The work has been on since 9:00. 2 The work started 9 hours ago === The work has been on for 9 hours / The work has been on since 9 hours ago. for 加时间段， since加时间点 9：00是时间点 9 hours是时间段