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.

Q: Article: The story happened during the Second World War. An old man lived in a small town of Germany. He had three sons and they all worked in the same factory where he had worked. After the war had begun, his sons were all made to join the army one after another and they all died in the fights. The old man was very sad. He didn't have enough food and was often hungry. And nobody helped him and he didn't know how to go on living. It was a very cold winter night. The old man couldn't go to sleep. He had been hungry for two days and it was so cold in his room that ice could be seen. He had to get up and began to run in the room until he lay down on the floor. The next morning he had to beg from door to door. He had been to a lot of cities and knew a lot. Once he came to a village, but the villagers were all poor and couldn't give him anything. He was too hungry to go to another village. He thought hard and found a way. He came to a police station and called out, "Hitler is a foolish pig!" Out came an old policeman at once. He took the old man into a room, gave him some bread and a cup of tea. Then he said, "Don't say so in our village, sir!" "I'm sorry, sir," said the old man. "I don't know it's Hitler's hometown." "No, no, sir," the policeman said in a hurry. "It's pigs' hometown!"
Answer: they had to do so

A: The old man's sons joined the army because _ .
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Q: Article: About five years ago, an American electrical engineer named Scott Brusaw and his wife Julie came up with the idea of putting solar panels on the ground rather than the roof. Then they began to develop the Solar Roadway. The Solar Roadway is an intelligent road that provides clean renewable energy using power from the sun while providing safer driving conditions, along with power and data delivery. They predict that the Solar Roadway will pay for itself through the generation of electricity along with other forms of income and that the same money that is being used to build and resurface current roads can be used to build the Solar Roadways. Each Solar Road Panel measures roughly 4 meters by 4 meters and contains a microprocessor that monitors and controls the panel, while communicating with neighboring panels and the vehicles traveling overhead. The inventors suggest that this provides a communications device every 4 meters on every road which could be used for example to warn drivers of cars which are moving across a centre line and various other speed control problems. The top of the Solar Road panels is made of super-strong glass that would offer vehicles the tractions _ need. According to the inventors, the Solar Roadway creates and carries clean renewable electricity and therefore electric vehicles can be recharged at any conveniently located rest stop, or at any business that has paved Solar Road Panels in their parking lots. The inventors say their Solar Roadway has many functions and advantages from main roads to driveways, parking lots, bike paths, sidewalks and runways. The Federal Highway Administration has given Brusaw $100,000 to develop the invention and Brusaw hopes to build a smart-road parking lot in the coming spring .
Answer: costs no more money than current roads

A: In the inventors' opinion, the Solar Roadway _ .
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Q: Article: If you were a pilot flying a plane, and suddenly the engine failed, would you eject , or stay in? For a pilot, the choice is very difficult. If he ejects, he is wise, but the plane crashes. If he stays in the plane, he risks his life. Recently, Chinese Air Force pilot Li Feng, 38, faced this choice during a training exercise. It was March 7 and he was flying a Jian-10 (Flghter-10) at 4,500 meters. A warning appeared on the plane's computer screen. He realized the plane might fail at any moment. Li Feng did a quick check of the engine and asked the base if he could return. When the fighter was 7km away from the airport, however, the engine stopped working. The plane began to fall at a speed of 25 meters a second from an altitude of 1,160 meters. Under Air Force rules fighter pilots may eject if their aircraft loses engine power below 2,000 meters and can't be restarted. Before Li lost contact with the control tower, the commander in the air base asked him to eject. But Li Feng insisted on having another try. "I knew where the deadline (to abandon the aircraft) was and was prepared for the ejection, but I decided not to give up unless the fighter was totally out of control," Li recalled during a recent television interview. After 104 seconds, Li was able to bring the fighter to a safe landing. The plane only suffered slight damage. "You are a hero! Congratulations!" Li's teacher, Xu yongling wrote in a text message to him after the landing. He said Li was a cool-headed pilot and very professional. Li's brave and calm act not only saved the 200 million yuan aircraft but also gave him invaluable first-hand experience of dealing with an engine emergency. For his outstanding performance, the Air Force recently awarded him a gold medal.
Answer: was asked to stay in, but he ejected

A:
When the engine stopped working, Li Feng _ .
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