In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.
One example: Article: There are a lot of public libraries in Britain. These libraries have more than one hundred and fifteen million books, not including those libraries of public schools. Public libraries not only lend books, music records but also help children, patients in hospitals and others to get special play readings, film shows and so on. The first public libraries were founded in about the year 1850. Today's public libraries usually have a reading-room, a lending room and a reference room. The greatest and most famous library in Britain is that of the British Library in London. It was founded in 1973 and has over 10, 000, 000 books. It has nearly every magazine, newspaper and book published in Britain and other parts across the world.
Answer: 10,000,000 or less.
Solution is here: How many books are there in the British Library?
Explanation: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.

Now, solve this: Article: "We don't have rush hours any more", said Mr. Charles Mac Lean, who runs the nation's busiest road. "We have rush periods, and they keep getting longer and longer." Mac Lean was describing prefix = st1 /Chicago's 235 miles of expressway. But the same might be said about almost any of the expressways that have become an important part of American city life--and about the heavy traffic that often blocks them. In Chicago, a computerized system has been developed that controls traffic on the city's seven expressways. Now one man--a controller--can follow the movement of Chicago's traffic by looking at a set of lights. The system uses electronic sensors that are built into each expressway, half a mile apart. Several times a second, the computer receives information from each sensor and translates it into green, yellow, or red lights on a map in the control room. A green light means the traffic is moving forty-five miles an hour, yellow means thirty to forty-five miles an hour and red means heavy traffic--cars standing still or moving less than thirty miles an hour. "See that red light near Austin Avenue?" the controller asked a visitor. "That's a repair truck fixing the road, and the traffic has to go around it". At the Roosevelt Roadentrance to the expressway, the light kept changing from green to red and back to green again. "A lot of trucks get on the expressway there," the controller explained. "They can't speed up as fast as cars." The sensors show immediately where an accident or a stopped car is blocking traffic, and a truck is sent by radio to clear the road. The system has lowered the number of accidents by 18 percent. There are now 1.4 deaths on Chicago's expressways for each one hundred million miles traveled, while in other parts of the country there are 2.6. Traffic experts say that the Chicagosystem is the "coming thing". Systems like Chicago's are already in use on some expressways in Los Angeles andHouston. "Chicago has taken the lead," saysNew York City's traffic director; and he adds, "We are far behind..."
Answer: By looking at a set of lights on the map in the control room.
Solution:
How does the controller follow Chicago's traffic?