Task: Question Answering
Input (English): Context: A person who is deaf when he is born is usually dumb as well. There may be nothing wrong with his mouth and tongue, but he cannot speak. This is because he cannot hear people, so he has nothing to imitate . He may try to make sounds himself, but cannot hear his own voice. However, even though he finds it difficult to speak and cannot hear, he can learn to read. Nowadays such persons can also be taught to speak because we have modern methods and equipment, but we did not have these when Helen Keller was born. Even with modern methods and equipment, however, it is not easy for deaf children to learn to speak, though most of them succeed. When a child is deaf and blind as well, it becomes much more difficult, though it is possible. Helen Keller was born in 1880. She became very ill at the age of nineteen months. Medical knowledge was not as great then as it is now. She did not die but lost her sight and hearing. As a result, she became dumb as well. Her parents did their best to teach her, but she couldn't speak by the age of six. Then, in 1887, a teacher, Miss Sullivan, came to live with her. Miss Sullivan herself had been blind. She had been partly cured. Though she could not see very well, she was not blind. Helen was a difficult pupil at first, but in a month Helen had learned how to understand signs and how to make them herself. At last in spite of her great difficulties, Helen learned to read, write and speak, even though she was deaf and blind. She even went to college and had full education. She wrote many books, and though other people have written books about her, her own books are the ones that best explain how it feels to be deaf, dumb and blind. Her best book is The Story of My Life. Perhaps you have read it. Though it was written in 1902, it is still a very interesting book. Even if you have not read it, you may have heard of Helen Keller. 
 Question: How long did it take Keller to understand signs?
Output (English): a month