大叔

In a sentence

• 我问大叔怎么去火车站。

  I asked the older man how to get to the train station.

  '大叔' here refers to a middle-aged man as a respectful and colloquial address.

• 这位大叔总是在公园里晨跑。

  This middle-aged man is always jogging in the park in the morning.

  '大叔' is used to describe a middle-aged man gently without referencing his name.

• 大叔，请问您知道这里的公交车时间表吗？

  Excuse me, sir, do you know the bus schedule here?

  Here, '大叔' is used respectfully to address a middle-aged man when engaging in polite social interaction.