tansiying 發表于 2012-5-23 16:01 ) i0 C+ r& ~( V6 r$ H% `7 YQ=V·A : b% F3 x( A2 R" [$ ]! c: E; B w V=φ(2P/ρ)½ , C0 j, W# D6 FA=π(D/2)²