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.

[EX Q]: Article: To prevent the deserts coming near, China has planted billions of trees---to replace destroyed forests and as barriers against the sand. This isn't a cure, though, say experts, as thirsty trees can make the problem worse by taking in groundwater. "Planting tress is one way, but it isn't that simple. It doesn't solve the basic issue of water resources," says Wu Bo, a professor. "We need to calculate how much water the trees will absorb, or else it could have a negative effect." Villagers in Zhengxin have taken on this challenge, with limited success. When the irrigation channels began to run dry, Lu Xianglin switched from wheat to cotton on his land. He also planted trees to protect his fields from sandstorms. He says he still gets good yields using flood irrigation and earns a good income for his family. Other farmers haven't stuck it out : about one in three have left Zhengxin in the past 10 years after their wheat crops died. Young people who can find jobs in the towns rarely return. Last week, Mr Lu joined the other men in his village on a government-arranged trip to see the land that has been set aside for their relocation, nearly 40 miles to the south. The next day, he was back, shaking his head at the plan. The idea of uprooting his family troubles him, as does the idea of giving up the land that fed his forefathers. He prefers to stay and keep up the fight. "With enough water, this problem can be solved," Lu says. "We can plant trees and grass, and they will grow bigger. That will stop the desert." Experts say that farmers could switch to drip irrigation to lessen their water intake for growing crops. Elsewhere in the region, farmers have built brick greenhouses as part of a plan to grow vegetables using less water. Roadside signs urge farmers to "Save Water, Protect the Environment".
Answer: it can make groundwater become less
[EX A]: The negative effect of planting trees in deserts is that _ .

[EX Q]: Article: I just finished the household chores for the night and was preparing to go to bed, when I heard a noise in the front of the house. I opened the door to the front room and to my surprise, Santa himself stepped out from behind the Christmas tree. He placed his finger over his mouth so I would not cry out. "What are you doing?" I started to ask. The words choked up in my throat, and I saw he had tears in his eyes. His usual jolly manner was gone. Gone was the eager, boisterous soul we all know. He then answered me with a simple statement"TEACH THE CHILDREN!" I was puzzled; what did he mean? Santa then reached in his bag and pulled out a FIR TREE ."Teach the children that the pure green color of the stately fir tree remains green all year round,describing the everlasting hope of mankind,all the needles point heavenward, making it a symbol of man's thoughts turning toward heaven." He again reached into his bag and pulled out a brilliant STAR. "Teach the children that the star was the heavenly sign of promises long ago. God promised a savior for the world, and the star was the sign of fulfillment of his promise." He then reached into his bag and pulled out a CANDLE. "Teach the children that the candle symbolizes that Christ is the light of the world, and when we see this great light we are reminded of he who displaces the darkness." Suddenly I heard a soft twinkling sound, and from his bag he pulled out a BELL. "Teach the children that as the lost sheep are found by the sound of the bell, it should ring mankind to the fold. The bell symbolizes guidance and return." Santa looked back and was pleased. I saw that the _ was back in his eyes. He said, "Remember, teach the children the true meaning of Christmas and do not put me in the center, for I am but an humble servant of the one that is, and I bow down to worship HIM, our LORD, our GOD."
Answer: he heard something unusual
[EX A]: Author opened the door when he was going to sleep because _ .

[EX Q]: Article: President Barack Obama speaks as he meets with Chinese President Xi Jinping over international security issues during the Nuclear Security Summit in Washington, March 31, 2016. While they report slow progress over major disagreements, what do average citizens in those countries think about each other? A study by the Pew Research Center offers some answers. Only 38 percent of Americans said they have a positive view of China, according to a 2015 Pew survey. And in China, only 44 percent of people surveyed gave the United States a positive rating. Americans expressed concern about the large amount of U.S. debt held by China and the loss of jobs to China. Last year, the U.S. Treasury Department said China held $1.2 trillion in U.S. government debts. People polled in China said they believe the United States is trying to prevent China from becoming as powerful as the U.S. The views reflect some of the tensions between the nations' leaders. The United States has been strongly against China's construction of artificial islands and military facilities along the disputed South China Sea. And there have been disagreements over how to respond to recent North Korean nuclear and missile tests. A joint statement from U.S. and China after Thursday's Obama-Xi meeting said both countries agreed to work together on nuclear security. The Obama administration said China has agreed to sanctions to protest recent North Korean nuclear tests. But Xi expressed opposition to a new missile defense system for South Korea, according to Chinese media reports. Such a system is being considered by U.S. and South Korean leaders to protect South Korea from a North Korean attack. At the start of his meeting with Xi, Obama said, "Of great importance to both of us is North Korea's pursuit of nuclear weapons, which threatens the security and stability of the region." Xi said China and the United States "have a responsibility to work together." As for issues dividing the two nations, Xi said both sides could "seek active solutions through dialogue and consultation." The two leaders met during a 53-nation conference on nuclear security in Washington, D.C.
Answer: Neither country was given a high positive rating from each other.
[EX A]:
According to a 2015 Pew survey, _ .