上個

In a sentence

• 上個週末我去了海邊玩。

  Last weekend, I went to the beach to play.

  In this sentence, '上個' is used to specify the timing, referring to the 'previous' or 'last' weekend.

• 上個班次的車已經發車了，我們需要等下一班。

  The previous bus departure has already left; we need to wait for the next one.

  Here, '上個' indicates sequence or order, referring to the 'previous' bus ride or timing.

• 這是上個世紀流行的音樂風格，現在已經很少聽到了。

  This was a popular music style from the last century, and now it's rarely heard.

  In this example, '上個' refers to the 'last century' in terms of historical period.