Instructions: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Input: Article: Real policemen, both in Britain and the United States, hardly recognize any similarity between their lives and what they see on TV -- if they ever get home in time. There are similarities, of course, but the cops (policemen) don't think much of them. The first difference is that a policeman's real life revolves round (......) the law. Most of his training is in criminal law. He has to know exactly what actions are crimes and what evidence can be used to prove them in court. He has to know nearly as much law as a professional lawyer, and what is more, he has to apply it on his feet, in the dark and rain, running down an alley after someone he wants to talk to. Little of his time is spent in chatting to charming ladies or in dramatic confrontations with desperate criminals. He will spend most of his working life typing millions of words on thousands of forms about hundreds of sad, unimportant people who are guilty -- or not -- of stupid crimes of little importance. Most television crime drama is about finding the criminal: as soon as he's arrested, the story is over. In real life, finding criminals is seldom much of a problem. Except in very serious cases like murders and terrorist attacks-- where failure to produce results reflects on the standing of the police -- little effort is spent on searching. The police have detailed machinery which eventually shows up most wanted men. Having made an arrest, a detective really starts to work. He has to prove his case in court and to do that he often has to gather a lot of different evidence. Much of this has to be given by people who don't want to get involved in a court case. So, as well as being overworked, a detective has to be out at all hours of the day and night interviewing his witnesses and persuading them, usually against their own best interests, to help him. A third big difference between the drama detective and the real detective is that the real detective lives in an unpleasant moral twilight . Detectives tend to have two opposing pressures: first, as members of a police force they always have to behave with legality; secondly, as expensive public servants they have to get results. They can hardly ever do both. Most of the time, some of them have to break the rules in small ways. If the detective has to deceive the world, the world often deceives him. Hardly anyone he meets tells him the truth. And this separation the detective feels between himself and the rest of the world is deepened by the simplemindedness -- as he sees it -- of citizens, social workers, doctors, law-makers, and judges, who, instead of putting a complete end to crime punish the criminals less strictly in the hope that this will make them reform. The result, detectives feel, is that nine-tenths of their work is re-catching people who should have stayed behind bars. This makes them rather cynical .
Answer: so that he can give a good reason for his arrests in court
Output:
It is essential for a policeman to be trained in criminal law _ .