TASK DEFINITION: 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.
PROBLEM: Article: NANJING -- Another human H7N9 case has been found in east China's Jiangsu Province, the provincial health department confirmed on January 31. The patient, a 75-year-old woman from the provincial capital of Nanjing, is in a critical condition. The case brings the number of infections in the province to eight this year. H7N9 has killed 19 in China this year, and the total number of human infections reached 96 on January 26, according to the Chinese Center for Disease Control and Prevention. With bird flu cases increasing on a daily basis, public concern over people-to-people transmission during Spring Festival is growing. Li Lanjuan, researcher at the Chinese Academy of Engineering and a specialist in H7N9 prevention, said so far there have not been any cases in which one person transmits the flu to another, and the latter transmits the virus to a third person. Her team has identified H7N9 virus mutations this year, but the _ are not large-scale. "Inter-human transmission is very unlikely," said Li, who added that the virus has not evolved to be extensively drug resistant. The National Health and Family Planning Commission said on Wednesday live poultry markets should close if any case of H7N9 avian flu is detected. The southern metropolis of Shenzhen has closed all live poultry markets until February 13 for a thorough cleaning. The city near Hong Kong has reported 14 human H7N9 cases since December 18. Live poultry trading has been halted in Hangzhou, Ningbo and Jinhua cities in Zhejiang, which reported the largest number of human H7N9 cases. China has stepped up research for an H7N9 vaccine in the face of the increasing threat from the virus. Beijing's Snovac Hotech Ltd.,which developed the A/H1N1 and H5N1 vaccines, said in a press release on Wednesday that it has completed preclinical studies of an H7N9 vaccine arid prepared several types for clinical testing. The company has submitted an application to the China Food and Drug Administration to start clinical trials.
Answer: It once developed the A/H1N1 and H5N1 vaccines.

SOLUTION: Which of the following is true about Beijing's Sinovac Biotech Ltd?

PROBLEM: Article: Why do we play sports?You might say "to get exercise"and you'd be right.To have fun? That's true,too.But there's more.In fact,there are at least 5 more reasons.According to the Women's Sports Foundation,girls who play sports get a lot more than just fit. Girls who play sports do better in school.You might think that playing sports will take up all your study time.But research shows that gilrs who play sports do better in school than those who don't.Exercise improves learning,memory,and concentration,which can give active girls an advantage in the classroom. Girls who play sports learn teamwork and goalsetting skills.Sports teach valuable life skills.When you work with coaches,trainers,and teammates to win games and achieve goals,you're learning how to be successful.Those skills will serve you well at work and in family life. Sports are good for a girl's health.In addition to being fit and keeping a healthy weight,girls who play sports are also less likely to smoke.And later in life,gilrs who exercise are less likely to get osteoporosis . Playing sports improves self-confidence.Girls who play sports feel better about themselves.Why?It builds confidence when you know you can practice,improve,and achieve your goals.Sports are also a feel-good activity because they help girls get in shape,keep a healthy weight,and make new friends. Exercise cuts the pressure.Playing sports can reduce stress and help you feel a little happier.How?The brain chemicals released during exercise improve a person's mood.Friends are another mood-lifter.And being on a team creates tight bonds between friends.It's good to know your teammates will support you--both on and off the field!
Answer: To tell us the benefits of playing sports

SOLUTION: What's the main purpose of the passage?

PROBLEM: Article: From furniture to jewelry, from the medical industry to civil engineering,three--dimensional printing can turn all sorts of ideas into objects. "I wanted to print large objects such as buildings,"said Behrokh Khoshnevis,professor of the University of Southern California.He planned to construct a house in 24 hours by applying 3D printing techniques,but he admitted there would be difficulties in meeting his goal. "For example,if you run out of ink while printing on paper,you will throw that paper away.But you cannot throw half completed buildings away if your material gets stuck,"he said.Although the printed house is not available to visit,there is a chance for people in Shanghai to see items printed in 3D. The Belgium-based company Materialize NV is currently holding a 3D printing exhibition in Shanghai that started in late 2012 and will continue until the middle of this year.The company is eager to show Asia what is possible with 3D printing. "All the pieces shown here are what cannot be made through traditional techniques. A good example of this customization is hearing aids More than l0 million people already use 3D printed hearing aids.all made according to the size of their ear."said Wim Michiels, executive vice-president at Materialise NV. "You can produce anything whenever and wherever you like.You don't need to set-up production lines for pieces that only need a limited amount of product.Setting up a production Line is a tot of work, takes a long time and is very expensive for a limited number of pieces" said Michiels. Kim Francois,managing director of Matcrialise China,said their European and American clients have at ready made the next step toward additive manufacturing with small-series production such as hearing aids.
Answer: Material.

SOLUTION:
According to Khoshnevis,what is the main difficulty in printing buildings?