abc=11/(ab+a+1)+1/(bc+b+1)+1/(ca+c+1)=1/(1/c+a+1)+1/(1/a+b+1)+1/(1/b+c+1)=c/(1+ac+c)+a/(1+ab+a)+b/(1+bc+b)=abc/(ab+a+1)+a/(ab+a+1)+ab/(ab+a+1)=(abc+ab+a)/(ab+a+1)=(ab+a+1)/(ab+a+1)=1楼上的结论是对的,...