user: Question: Article: A mother had two daughters. She loved them very much, but two girls would fight with each other from their earliest years. As they grew older, they became total strangers. They had no contact with each other when they were adults. This caused the mother great pain. Then, later, she had an idea. She decided to write a letter to them. In this letter, she told them how much she loved them, and how she wanted them to love each other in this way. She also gave them news of herself and some guidance on how to live happier lives. When the letter was ready, she wrote out one copy for each daughter, but these copies were special. Each copy contained only every second sentence of the original letter: the copy for one daughter had only the even   sentences, and the other daughter's copy contained only the odd sentences. Neither contained the fullness of the mother's message. When the two daughters received their letters, they were puzzled. To understand the half-letter, they would have to put the two letters together and read them as one, which meant they must approach one another again in love and respect. But they each blamed the other for not helping them when trying to read the half-letter. For a long time, the mother waited in vain. Then one day, when the mother had almost given up hope, there was a knock at the door. There they stood, together. "We've come home," they said at the same time. "We've finally put our letters together, and we've come to say how much we love you, Mum." Then she hugged them both, tears of joy streaming down her cheeks, and welcomed them back home. Question: Why did the two daughters visit their mother at last? Yes or no, is the answer "They felt grateful for the mother."?
Answer: Yes

Question: Article: On a cold winter morning in the late 1930s, Bobby awoke early. It was a day that Bobby would never forget. Bobby, his brother and his mother were once again abandoned  by his father. When times got hard, the man left home. Bobby wasn't surprised. He must take the responsibility for caring for his family.  He put on the warmest clothes he had and pulled on his old socks and torn shoes. After thinking of a way to keep his feet dry, he went outside looking for work. Coming across some men working on the road, he joined in and worked hard for hours. Suddenly, rain poured down. "Go home and get out of this weather," the men shouted, giving him a few coins. Bobby used the money to buy as much food as he could afford in the nearest store. While holding a small bag of food ,Bobby stopped to adjust  the thick paper in his shoes. A man, who was a member of the Salvation Army, saw Bobby's problem. He bought Bobby a new pair of shoes. I wasn't there on that cold day. But I've heard the story many times and can always imagine my father, as a child, dancing and wearing a pair of new shoes home. Several years later, Bobby joined the navy. He continued to support his family and meanwhile worked for the Salvation Army so that another little boy somewhere might receive a new pair of shoes for Christmas. The tradition lasted until my father became too ill. Daddy died six years ago. While the new shoes kept his feet warm in the 1930s, Daddy's act of giving back for tens of years warmed his heart in a greater way. Question: How did the men working on the road treat Bobby? Yes or no, is the answer "They gave him some money"?
Answer: Yes

Question: Article: Most people know Alexander Graham Bell invented the telephone. But not many know about another talking device (equipment) he invented just four years later, in 1880. He called the device the photophone. "Photophone" comes form the Greek words for "light" and "sound". The photophone did not use electricity to carry sound over wires between two people.  _ . Instead, the photophone used a beam of sunlight traveling through the air. With his invention, Bell could actually transmit   human speech on a beam of light. To do so, he spoke close to a thin mirror that was reflecting sunlight. The vibrations   of his voice caused the mirror to vibrate, and the vibrating mirror caused the light to vibrate. The vibrating light hit a light-sensitive cell in a receiver placed some distance away. The cell changed the light patterns into electrical signals. Earphones changed the signals back into sounds. Bell believed that his idea of talking on a beam of light would prove to be important. He often called the photophone his greatest invention. Even though the photophone depended on a source of energy that was not constant--the sun--Bell wasn't a bit discouraged. He felt sure that people would one day talk using beams of light. Two much more recent developments made Bell's dream come true. In 1960, a scientist built the laser. A laser produces a highly concentrated beam of light. Shortly afterward, other scientists developed a new kind of optical fiber. The optical fiber is a glass thread. The new fiber could carry light beams long distances--as far as several miles. Question: According to Bell's own opinion,   _  is his greatest invention. Yes or no, is the answer "photophone"?
Answer:

assistant: No