Q:Write a multi-choice question for the following article, with the given choices and answer: Article: On June 6th, 2012 Tiangong-1 welcomed its first guests, the Shenzhou IX manned spacecraft . The Shenzhou IX has two male astronauts and one female astronaut. At that time, Liu Yang, a thirty-three year-old woman, became the first Chinese woman in space. Joining the People's Liberation Army (PLA) Air Force in 1997, Liu Yang became an experienced pilot after flying safely for 1,680 hours. In 2010, she became an astronaut because of her good job. "When I was a pilot, I flew in the sky. Now that I am an astronaut, I will fly in space. This will be a much higher and farther flight. I always couldn't help wondering: What would the Earth look like from outer space?" Liu said. In June 2012, Liu took Shenzhou IX to the space as China's first female astronaut. "I have full confidence," Liu said before the task. "There are many foreign female astronauts that have been into space. Men and women have their own advantages in carrying out space tasks. They can encourage each other and better complete their task. However, the difficulty of her training has not affected her life's pleasure. "I love children and I love life. I love reading, especially novels and history books. I am also a great cook. To be with my family is one kind of happiness, but to fly is another kind that people can't experience." "I am grateful to the motherland and the people. I feel honoured to fly into space on behalf of millions of female Chinese citizens. " Liu said after coming back to the Earth safely. Options: A 18 B 33 C 31 D 25 Answer: C 31 Question:
A:
Liu Yang worked as an astronaut when she was _ years old.