设 = (x,y)|{x)^2+(y)^2leqslant 9} 则-|||-=(iint )_(D)(|{x)^2+(y)^2-4|dxdy=} () .-|||-A pi (int )_(0)^3r((r)^2-4)dr:-|||-B pi (int )_(0)^3r|(r)^2-4|dr:-|||-C pi (int )_(0)^3r(4-(r)^2)dr:-|||-D pi (int )_(0)^3|(r)^2-4|dr