I would like to know that in Islam you are not allowed to show hair from you body to ghair mehrams, so then what about your eyelashes, because now in your hijab you get the holes for eyes from which you can see your eyebrows.

If it is not permissible to show hair to a strange person then it is also not permissible to show neither skin nor the face. But because of the necessity the eyes are kept open and exposed it is allowed for the eyebrows to be shown.
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