American Sign Language: Yes/No Facial expression.

You should raise your eyebrows near the end of questions to which there is a "yes" or "no" answer.

YES/NO facial expression:

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Note: The "Yes/No" facial expression is one of many "nonmanual markers" (NMM) used in ASL.
For more information, see:  Nonmanual Markers (NNM)
Also see: "WH question facial expression"