Chris is not a common explorer (探险家). He usually works in an office for a large organization. Yet his job can sometimes be just as     21     and dangerous as being an explorer.

Chris works for MSF, an organization also known as Doctors Without borders (无国界医生). MSF sends trained doctors all over the world to help people after a war or a     22     . Chris is a doctor from France who has travelled to many places to help people.

At the moment, there are more than 27,000 trained doctors and nurses taking part in MSF projects and tasks. All kinds of doctors can     23     for MSF. They need to be prepared to go almost anywhere in the world and, of course, they should expect difficult conditions. Doctors with     24     in tropical (热带的) diseases are especially useful because most of MSF's work is in Africa.

When MSF accepts a doctor for a task, he has to go for at least six months. When doctors have completed a few tasks, they might be sent on another     25     task, such as an earthquake.

But why would a doctor leave a     26     life and a good pay to MSF? According to Chris, the experience you gain is a great help in your work. Besides, just like the explorers of the past, you need to keep an open mind and learn to     27     the people you meet. Above all, at the end of each task, you have made a real     28     to people’s lives.

Most of the boys want to be explorers, and the two brothers are among them. For Ollbie and Harry, life is an adventure. For the past several years, the brothers have been working to _______ a list of 500 challenges and experiences.

"The idea came about actually from the boys," their father, MacNeill Ferguson, said. "The boys were just asked one day if they could come up with some cool things for us to do as a family. They _______ some impossible ideas firstly, like going on a trip to Mars, International Sausage Day and all kinds of _______ kids' requests. They built the list to a hundred, then kept finding new things they wanted to go and try... until it got up to 500." They're all listed on the brothers^' Facebook page.

So far, they have built an igloo (圆顶小屋),explored the wilderness, and sent their Lego men to the depths of the ocean and into outer space. Perhaps their biggest adventure is playing out right now on the high seas. Last year, Ollbie and Harry's "Adventure", one of their toy ships _______ from the Scottish coast. It sailed across the North Sea to Scandinavia. It then began a ride on a Norwegian boat and was launched again. _______, they had equipped the toy ship with a tracking device (跟踪器). It allowed the brothers to know every step of the sailing well. But the battery on the tracking device is becoming weak, so Harry and Ollbie hope a passing ship notice their boat and is able to recharge (充电) its battery, allowing the trip to continue.

"I want it to go to Australia because that would be halfway around the world, and there's lots of beaches there," Ollbie said.

"Harry, where would you like the boat to go?" Ferguson asked. Without any _______, Harry replied, "that would be China because we all love China.^" He thought that even there were so many difficulties the boat would reach China.

Although most of us are now stuck at home due to the virus outbreak, there are still many people trying to do some sports not only to kill time, but also to help themselves and others stay a    56     this difficult period.

Gymnasiums and basketball courts are c    57    , so many of us choose to keep fit at home, which helps us improve our immunity (免疫力).

Fitness apps are becoming more p    58     these days. Downloads of this kind of apps are growing rapidly, China Daily reported. For example, an online exercise platform called Be Fit offers online exercise lessons for people of different ages. They're easy to f    59     and all you need is some basic fitness equipment, like a yoga mat (瑜伽垫). Some fitness clubs have had to shut up their business in their training ground. But they've encouraged their personal trainers to make videos and share them on social media platforms for people who exercise at home.

Shanghai started online courses for students in March, i    60     PE classes. PE teachers use livestreaming (直播) soft wares or record video clips as guidance for students. Li Xiao, a PE teacher, has made an exercise video for her students. She told us that she advised her students to make use of simple tools, such as plastic bottles to do the exercises. The exercise doesn't require much s    61     and is suitable for exercising at home.

Some parents choose to play t    62     games they played in their childhood to keep children positive, such as throwing darts (掷飞标),pinching marbles (夹弹珠). For example, a couple from Shantou, Guangdong recreated childhood games for their children. The children throw homemade cardboard hoops (圈) over small objects, such as wine bottles. In this way, the whole family got involved.

What homework did you do in the winter holiday? Now homework is not simply about exercises. It can be researches, experiments and even work experiences. Take a look at some students' special homework.

One day, Wang Yang, from Shanghai Oriental School, was doing his biology homework. His teacher asked them to research the nutrients of different snacks. He bought 10 kinds of snacks. Then he checked their ingredient (成分) lists one by one and wrote down the amount of sugar, fat and so on, in each. ''We are told it is not good to eat too many snacks. They have high calories (卡路里). But we always pay no attention to it," he said. After analyzing (分析) each snack's ingredients, he realized it was true.

Wang Yang spent three days on the homework. But he said it was interesting. "I learned a lot. I collected the data (数据), created forms and wrote the report by myself."

With some plasticine (橡皮泥), steel balls, a ping-pong ball, could you make a turnbler (不倒翁)? This is the physics homework of Huang Jiali, 14, of Shanghai 54 Middle School.

Huang first cut the ping pong ball in half. Then she put the plasticine and steel balls into one of them. The bottom of the turnbler was made. Finally, she also used the paper to make the "hat". "Next term, we will learn about the center of gravity (重心). This homework made me more curious about it," she said.

While Wang and Huang did their homework at home, Ding Ling, 15, of No. 5 Middle School, had to go outside. She worked as a guide in the local museum. ''Everyone at our school has to take part in volunteering or other activities," she said.

Ding was a guide in the gallery (展馆) of coins. She got brochures (小册子) from the museum. In order to make the introduction more vividly, she still did research and added more information to her introduction. She worked three hours a day and had no time to take a break. But she felt it was a meaningful experience, "I learned how to do some research, and my communication skills are also improved." she said.

69. In at least 60 words, write a letter to the person you want to express your thanks. 请以"A thank-you letter to ________"为题，写一封不少于60个词的感谢信，标点符号不占格。

2020年是不平凡的一年，在这段特殊的日子里，你一定感受到了父母、老师、朋友或是一些陌生人给你带来的温暖和感动，请结合自己的经历，写一封信给他（他们），表达你的感激之情。