A

    Many people think the camel stores water in its hump (驼峰), but it does not. Instead, the camel stores something else there—food. The camel's hump is really a hump of fat (脂肪). The camel is often called "a ship of the desert". When the camel is not travelling and is in a place where there is much food and water, it eats and drinks a lot. As it does so, its hump rises from the fat its body makes. Then, when the camel is travelling through the desert and when there is no food, it can live off the stored fat.

    A camel can go on for days or weeks with little food or water. However, when its hunger reaches the starvation (饿死)point, its hump shrinks (收缩) and may even slip off its back and hang down its side.

    Camels are not fussy (挑剔的) about what they eat. Thorny (多刺的) plants don't hurt their mouths, grass of any kind will do and so will hay, dry grain and cactuses (干草, 干粮, 仙人掌).

There are one­ hump camels and two­ hump camels. Camels with one hump are called Arabian camels. They come from North Africa. Camels with two humps are from Asia.

    On July 20, 1969, Neil Armstrong became the first person to walk on the moon. The space suit Armstrong wore on his lunar mission has come to symbolize courage and human achievement. In 1971, the Smithsonian's National Air and Space Museum(NASM), in Washington, D.C., acquired (获得) Armstrong's suit. It stood proudly on display for visitors to admire, until there were changes in the suit's appearance. "Over time, the suit started to show signs of deterioration," Lisa Young said. Young is an objects conservator (文物修复员) at NASM. It is her job to preserve(维护)historical and cultural objects.

    "Plastics are tricky to conserve," Young says. They tend to degrade (降解)over time. Neoprene is one type of plastic in Armstrong's suit. The material can turn brittle and break into tiny pieces. This would ruin the space suit. NASM, seeking ways to preserve this historical treasure, removed it from display in 2006.

    What causes plastic to degrade in the first place? "Many things," Odile Madden says. Madden is a scientist in California. She explains that sunlight, water, humidity, and dust can cause plastics to degrade. "Some plastics will break down no matter what we do," Madden says.

    Yet history can still be saved. Scientists have found that storing plastics in cooler temperatures, with lower humidity levels, can slow degradation. Young says Armstrong's suit is currently in storage at a temperature of 63°F and a lower relative humidity of 30%. These conditions will be maintained when Armstrong's suit returns to a museum display case in time for the 50^th anniversary of the moon landing.

    Plastic degradation affects art, too. Artist Claes Oldenburg created False Food Selection in 1966.It consists of plastic food displayed in a wooden box. The plastic food used to look real. Now, some of it has flattened and yellowed. Georgina Rayner is a conservation scientist at Harvard Art Museums, in Cambridge. She says the artwork's wooden box produces an acidic (酸的) gas that eats away at the plastic. This speeds up the degradation process. But Rayner is motivated to conserve this artwork and others like it. "Plastics are a part of our history," she says. "It's important to preserve them so that future generations can understand the journey we've taken."

    There are many animals in danger, such as pandas, elephants, and South China tigers.

    The South China tiger is the smallest tiger in Asia. It is also one of the rarest tigers in the world. Scientists think that there might be a few South China tigers living in the wild, but they are still not sure about it.

    The South China tiger is special in its face, but it shares the height with the common tigers. In the past, the South China tigers lived in the forests. But today more than half of them are living in zoos. If there are not safe places for them, they will die out soon. Baby South China tigers need their mothers' milk in the first two months. The mother teaches her babies how to hunt.

    Scientists think that people should do something to protect the rare animals. If people take action together, these animals will have a better place to live in. We'll also live in a better world.

Feet are an important part of you. Without them, you couldn't stand up, walk or run around. Your feet work so hard that sometimes they get sweaty (出汗).

Think of a hot summer day when you have been walking around all afternoon. Your feet have been in those trainers for a long time! The moment you take off your shoes, you feel good and relaxed, but your feet smell bad. You may think it is because of the sweat. But in fact, sweat itself has no smell. It's the bacteria (细菌) on your skin (皮肤) that mix with it and gives off a bad smell.

Bacteria love dark and wet places like the inside of sweaty shoes. The sweatier you get, the more bacteria there will be. When you wear your shoes, bacteria will have a good meal on your feet. They eat dead skin cells from your skin and then leave a kind of waste called organic acids (有机酸). These organic acids smell bad. Things will become better if you wear cotton socks.

A. City Walk makes traveling and shopping more popular.

B. You can find happiness in the great things along the way.

C. It shows that some young Chinese prefer real local experiences. 

D. They take a walk through cities, shopping around and taking photos.

E. In our country, travelers in the last Golden Week holiday was 481 million.

F. Since then, many local tourist groups have started offering City Walk products.

The latest way of exploring urban（城市的）China is now the City Walk. While some people travel home and abroad, others like a more relaxing time without going out of town. {#blank#}1{#/blank#}.

In the traditional way of traveling, young people often visit well-known places. However, the goal of City Walk is to enjoy local culture and lifestyle, instead of going to "must-see" spots（景点）. {#blank#}2{#/blank#}. Therefore, their explorations often include not only parks, but even local food markets.

Jack Zhang, a social media expert in Shanghai, decided to stay in the city after a disappointing Labor Day travel experience. This time, he walked around Yuyuan Road, watched the elderly playing cards, and relaxed in a coffee shop. "The City Walk allows one to experience the slow life. {#blank#}3{#/blank#}. And you can think about your personal life like you hardly do when you are busy," he said.

This way of traveling became popular in July after getting attention on social media. {#blank#}4{#/blank#} Tourist groups in big cities like Beijing, Shanghai and Chengdu provided official City Walk maps and guides with tips. According to Wang Yi, a college professor, " {#blank#}5{#/blank#}. It may help improve the real economy（实体经济）in the future."