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Few people would even think of beginning a new job at the age of 76, but one of America's most famous artists did just that. Anna Mary Robertson, better known as "Grandma Moses", turned to painting because she was too old to work on her farm.
Grandma Moses painted carefully and her works were nice. She first painted only to enjoy herself, and then began to sell her works for a little money. In 1939, a collector, Louis Caldor happened to see several of Grandma Moses' works hanging in a shop. He liked them, bought them at once, and set out to look for more. Caldor held a show to introduce the works of Grandma Moses to other artists.
Grandma Moses died on December 13, 1961, at the age of 101. She was world famous.

答案解析：
(1) 正确答案为A。根据Few people would even think of beginning a new job at the age of 76, but one of America's most famous artists did just that. 很少有人会在76岁的年纪才开始从事一项新工作，但是美国最著名的艺术家之一便这么做了。可知，摩斯奶奶是在76岁开始画画的，因此A项正确。
(2) 正确答案为B。根据turned to painting because she was too old to work on her farm. 开始画画，因为她年纪太大了，不能再在农场上工作了。可知，摩斯奶奶在成为艺术家之前是在农场上工作，因此B项正确。
(3) 正确答案为A。文章主要介绍了Anna Mary Robertson（安娜·玛丽·罗伯逊）这位高龄画家的故事，因此A项正确。