"Is that so?" I asked in amazement. As far as I knew no single couple had gone through life without a quarrel; even the most affectionate couples on earth quarreled sometimes.And according to a survey by the United Nations, divorce cases among human couples had increased in recent years. 

"Don't you know the famous three laws of the robot?" The general manager stared at me in surprise, apparently wondering how I could be so ignorant. Then he pointed at a panel of white marble at the centre of the supermarket on which the three laws of the robot by Asimov were inscribed,glistening in the lights: 

First law: A robot may not injure a human being or,through inaction, allow a human being to come to harm. 

Second law: A robot must obey the orders given it by human beings except where such orders could conflict with the First Law. 

Third law: A robot must protect its own existence as long as such protection does not conflict with the First and Second Laws.