因为abc=1.所以(1)a/(ab+a+1)=a/(ab+a+abc)=1/(bc+b+1).(2)c/(ac+c+1)=c/(ac+c+abc)=1/(ab+a+1)=abc/(ab+a+abc)=bc/(bc+b+1).(3)原式=1/(bc+b+1)+b/(bc+b+1)+bc/(bc+b+1)=(bc+b+1)/(bc+b+1)=1.所以原式=1.