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.
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Question: Article: Who Owns the Moon? Within the next ten years, the U. S., China, Israel, and a crowd of private companies plan to set up camp on the moon. So if and when they plant a flag, does _ give them property rights? A NASA working group hosted a discussion this week to ask: Who owns the moon? The answer, of course, is no use. The Outer Space Treaty, the international signed by more than 100 countries, states that the moon and other celestial bodies are the province of all mankind. No doubt that would annoy all of the people throughout the ages, like monks from the Middle Ages, who have tried to claim the moon was theirs. But ownership is different from property rights. People who rent apartments, for example, don't own where they live, but they still hold rights. So with all of the upcoming missions to visit the moon and beyond, space industry thought leaders are seriously asking themselves how to deal with a potential land rush. " This is a very relevant discussion right now. We've got this wave of new lunar missions from around the world," said William Marshall, a scientist in the small-spacecraft office at NASA, but who spoke this week at an event hosted by NASA's Co Lab, a collaborative public-private working group. He was speaking from his personal interest and not on behalf of the agency. To be sure, the United States aims to send astronauts back to the moon by as early as 2015, in a mission that would include a long-term settlement. China and Israel, among others, are also working on lunar projects. And for the first time, several private groups are building spacecraft to land on the moon in an attempt to win millions of dollars in the Google Lunar X Prize. Some participants say that they plan to gain some property rights in the mission.
Answer: no one can answer the question " Who owns the moon?"

Answer: In the passage the writer seems to be worrying that _ .

Question: Article: Lying on his sickbed in hospital, all 86-year-old Lin Ruiming can do is stare out at a tiny part of sky through the small window. The old man used to ride his motorbike through the busy streets of downtown Beijing. All the while he could only dream of touring the world. He has been suffering from terminal lymphoma since February. As a last gift, his granddaughter,Lin Yifan,asked China's Internet population to give her grandfather a shot at globetrotting . Last week, Lin Ruiming's _ from Sydney Harbor, Australia, to the River Thames in London, UK, and even to a volcano in Auckland, New Zealand. Lin Yifan, 29, had promised to paint a portrait of her grandfather, but had almost forgotten her word until the old man got ill. "I had put off the painting for many years because I believed I would have plenty of time to do it," she said. She spent one evening last week working on a portrait, based on a photo taken on her grandfather's birthday last year. She posted the portrait on Sina Weibo, and called for Web users to take photos with the portrait in different locations and send them to her on May 11.Over the following five days she received about 20,000 photos, most of which were sent by people she had never met. She says that her grandfather, while too weak to view all the photos, has said that he is happy. "Thanks to all these helpers, I have become a celebrity around the world," the old man joked.
Answer: she believed she could do it anytime

Answer: Lin Yifan put off painting the portrait mainly because _ .

Question: Article: Mark Twain was my hero when I was nine because that was when I discovered Tom Sawyer. But even at the height of my admiration, I couldn't agree with him that Anne, the main character inAnne of Green Gables, was "the dearest and most loveable child in fiction since the best-known Alice". I had readAnne of Green Gables as well asTom Sawyer, and she had made me as sick as a dog. Another Mark Twain's quote will explain my problem. He said, "When I was a boy of 14, my father was so ignorant that I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years." I gradually understood his words as growing up. When I picked up the book again a few years later, I too was astonished at how much it had improved--and shortly afterwards shocked by the fact that not only could I be a fool in all sporting, artistic and practical matters, I could also be so when it came to reading too. On rereading, then, I learned that Anne is indeed a dear and most lovable child. I couldn't help adoring the girl who insists that her name be spelled with the "e" instead of Ann as she believes that is "so much more distinguished." She is a brave and determined survivor of a severe upbringing who has refused to let her circumstances crush her spirit. She arrives at Marilla and Matthew Cuthbert's farm with everything unfavorable--orphaned, unwanted and her biggest trouble of red-hair and freckled face. However, she gets along well, through her strange way of seeing things, through her honest love of beauty and lovable attempts to master her unreasonable desires. She finally wins over the Cuthberts, their neighbors and millions of readers who have met her over the 101 years since the book was first published. When I settle down with it these days, I've come to see the truth in Mark Twain's praise for the book, and this reminds me of the great truth that you are never too young to start rereading.
Answer: people's attitude may change

Answer:
By referring to Mark Twain's remark on his father, the writer wants to prove that _ .