I sent my wife to emergency that afternoon. It looks like she hurt her tailed bone. It is not necessary to take a operate right now. The only thing is she feel very painful and the pain will last 1-2 weeks. It looks like nothing worse than that, and she feel better and better now. Thanks for the help from Bloor, Bloor's wife and their cute angel. Also, thanks for the help from other friends which I don't know the name now. I hope my wife can recover and join the activity very soon. We can introduce each other at that time.