This is the 735th most frequent Chinese word.
當時
"At that time" or "then."
Here, "當時" is used to refer to a specific past moment or period when the action of the sentence occurred.
當時我正在學習中文。
At that time, I was learning Chinese.
In this sentence, "當時" sets the context as a point in the past under discussion, referencing the time of the relevant events.
你還記得當時發生了什麼嗎？
Do you still remember what happened back then?
"當時" is employed here to indicate the speaker's belief or perception during a specific past timeframe.