input question: Write a multi-choice question for the following article, with the given choices and answer: Article: This is a tale of two friends --- one is blind, the other has no arms. On their own, the two are "disabled". But together, they are a powerful team that has changed part of their village in North China's Hebei Province into a rich, green forest. Meet 53-year-old Jia Haixia and Jia Wenqi! Their story began in 2000, when Haixia, who was already blind in his right eye, lost his left one after an illness. Wenqi lost his arms in an accident when he was just three. Neither could find a job, so the two decided to team up. They rented some poor land and began to plant trees. In return, the local officials paid them a small fee. Haixia and Wenqi never imagined that they would end up creating an environmental paradise. Their forest now has over 10,000 trees, hundreds of birds and many other wild animals. In addition, it saves the village from river flooding during the rainy season. When the friends work together, they focus on their strengths not their disabilities. Their day begins at 7 a.m. when the sightless Haixia carries Wenqi across the river to get to their worksite. Since they cannot afford to buy young trees to plant, the two use branches from existing trees. Haixia climbs to the tree-top and with Wenqi's direction, selects the perfect branch. He then digs a hole and carefully plants it. Finally Wenqi waters the area. Though hard-working, the men don't make much money. But as Wenqi puts it, " _ ." Neither Haixia nor Wenqi cares about money. Together, they already have everything they need --- a perfect pair of eyes, two strong hands, and the best friendship in the world! Options: A They are easy to get. B They do not cost money. C They can grow very quickly. D They are preferred by animals. Answer: B They do not cost money. Question:???
output answer: Why do Haixia and Wenqi plant tree branches?

input question: Write a multi-choice question for the following article, with the given choices and answer: Article: Camilla Chomp was a strange little girl. She liked to spend her time alone eating chocolate. Her parents were worried, so they took all the chocolate away. Camilla left her house to look for some chocolate. She found a small house full of bottles. Among the bottles, a blue bottle caught Camilla's eyes. It was full of chocolate. In the bottle there was also a card with the words "Change tears into chocolate." Camilla was very excited. She ran out of the house with the bottle to look for someone crying. First, she met a little boy crying hard and collected his tears. The tears were quickly changed into chocolate. While Camilla was collecting the tears, she comforted the boy. Finally, the boy stopped crying and they had a good time together. Later, Camilla met a woman and an old man crying. The woman had broken some bowls. And the old man's dog had just died. Camilla collected their tears and made them happy again. Soon, Camilla knew that making people happy was much more important than finding chocolate. So she stopped collecting tears and began to help sad people. As a result, she had many friends and had a happy life. Options: A eat chocolate B read books C collect coins D eat fruit Answer: A eat chocolate Question:???
output answer: Camilla liked to _ .

input question: Write a multi-choice question for the following article, with the given choices and answer: Article: Men have always wanted to fly like birds. Birds can fly easily because they are light,but men's bodies are heavier. Men first went up into the air in balloons. These were big bags,and they were filled with gas. Hydrogen is a useful gas for balloons. It is lighter than air. _ is also lighter than air,but it costs a lot of money. So balloons are usually filled with hydrogen. Balloons have to fly with the wind as they have no engines to drive them. Later,men made airships. They are balloons with engines. They are also filled with hydrogen. Aircrafts with wings now take people across the world. Powerful engines drive these machines across the sky. Some of the engines are like the engines of cars,but they are more powerful. There is another kind of engine,we call it the jet engine. An English engineer invented the jet engine. At the same time,Germans were also building a jet engine. In May 1941,the English engineer's new engine was fixed in an aircraft,and the aircraft flew quite well. Jet engines are very powerful. Usually two to four are enough for an airplane,but some big aircraft need six. Anyone in a moving jet plane can feel the power of the engines. Jet planes can travel faster than sound. As a flying jet plane leaves its noise behind,we do not hear it until it has gone. Options: A jet planes are very powerful B jet planes have enough jet engines C anyone can feel the power of the engines D jet planes travel faster than sound Answer: D jet planes travel faster than sound Question:???
output answer: We don't hear the flying jet plane's noise until it has gone because _ .

input question: Write a multi-choice question for the following article, with the given choices and answer: Article: Friends are important in our lives, but how to keep our friendship is more important. Here are some ways for you. Write letters If your best friend moves to other cities, you could buy the same magazine, E-mail, phone or write each other about the articles in the magazine that make you laugh. This will make you have the same interest. Don't forget to visit each other as often as you can. Think of your friends first What are your friends' thoughts, dreams, hopes and fears? What are her past experiences ? From these, you could think of ways to support your friends. You put your friend first, she or he feels special, and you both grow closer to each other. Gifts from the heart Take photos of a whole day or weekend together. Write a short story about your time you enjoyed. Save the movie tickets, restaurant stubs or special gifts you find every place you travel. Put everything in a box you'll keep all the time. Create your own fun ways to keep your friendship if you can. Options: A make friends B find good gifts C create our own fun D keep friendship Answer: D keep friendship Question:???
output answer:
The writer wrote this article to tell us how to _