因为原式=2c/a+2c/b+2b/a+2b/c+2a/b+2a/c
=(2c+2b)/a+(2c+2a)/b+(2b+2a)/c
而a+b+c=0,所以b+c=-a,c+a=-b,b+a=-c
所以原式=-2-2-2= -6