pretty holes only
u5317 u90e8 u6ac3 u59d0
u6211 u7684 u53cb
u5ac2 u5b50 u8f7b u8f7b u4e00 u78b0 u5c31 u5df2 u7ecf u6e7f u7684 u7684 u4e0d u884c u4e86 u3002