Modal particles, also known as 语气助词 (yǔqì zhùcí) or 语气词 (yǔqì cí), are words used at the end of sentences to indicate mood, or attitude. They tend to be neutral tone and hard to translate, but they add a bit of “flavor” to a sentence. – Chinese Grammar Wiki
A separate collection of video Lessons is coming soon regarding 了 (le).
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