曾於

曾於

"曾於" means "once at" or "once in," indicating something that occurred or existed at a certain place or time in the past.

The word '曾於' is used to indicate a past occurrence, showing that the action took place 'last year.'

他曾於去年參加了馬拉松比賽。

He participated in a marathon last year.

Here, '曾於' is used to specify the timeframe 'during elementary school years' of the past activity.

我曾於小學時代學過書法。

I learned calligraphy during my elementary school years.

In this sentence, '曾於' implies past duration and location of the event, 'worked abroad.'

她曾於海外工作多年。

She worked abroad for many years.