a mystery to (one)

Something that is difficult to understand. Why she walked out in such a huff this morning is a mystery to me! She was acting normally before that. It was a mystery to scientists where the birds migrated to until they banded some of them and tracked their movement.

Common Names:

Name	Pronounced	Usage
Lucila	-	Spanish
Ru	-	Chinese
Ed	ED (English), ET (Dutch)	English, Dutch
Pollard	['pɔləd]
InÉS	ee-NES	Spanish
Julia	JOO-lee-ə (English), YOO-lee-ah (German, Swedish, Danish, Finnish), HOO-lyah (Spanish), YUWL-yah (Polish), YOO-lee-yah (Russian), YOO:-lee-ah (Ancient Roman)	English, German, Swedish, Norwegian, Danish, Dutch, Spanish, Polish, Finnish, Russian, Ukrainian, An