Animals need to sleep to stay healthy. But sleeping can also be dangerous because other animals may hurt (伤害) those who are sleeping. Don’t worry. Here are many different ways of sleeping. They help the sleeping animals stay safe (安全). Some of these ways are quite funny.

All bats sleep upside down. They hang from a tree. Up high, bats are safe from most other animals. If some dangerous animals come, they just fly away.

Horses often sleep standing up. Their legs lock (固定) in place. If a horse is lying down, it needs a long time to get up. A horse can run from danger quickly if it is standing.

A flamingo can sleep when standing on one leg. The standing leg locks and the other leg is near the flamingo’s body. Its head rests on its back. A flamingo lives and sleeps near many other birds to stay safe.

Would you like to sleep in the way they sleep?

Remember the story called The Thirsty Crow（口渴的乌鸦）? A smart thirsty crow succeeds in getting water by dropping stones in a bottle. A piece of news in Sweden turns out the story is true.

The news says a Swedish company called Corvid Cleaning is training wild crows to pick up cigarette butts（烟蒂）from the streets of Södertälje, a city not far from Stockholm.

Trash is bad for the environment in many ways. For example, animals (both on land and in the ocean) often mistake trash for food and eat it. Sometimes they even die because of that. Cigarettes are one of the most dangerous forms of trash.

________ Through a machine. The crows are trained to put the cigarette butts into the machine. If the machine makes sure the thing is a cigarette butt after scanning（扫描）it, the crows will get food from it as a reward（回报）. Sounds interesting, right?

According to Christian Günther-Hanssen, the founder of the company, with crows’ help, they don’t need to spend so much on the cigarette butts cleanup. “Crows are known to be one of the smartest animals in the world. They’re easier to teach. At the same time, there’s a lower risk of them eating any trash by mistake,” Christian said.

The crows for the cleaning job are still living in the wild, and they are free to stop the project at any time. If they keep coming back to Corvid Cleaning’s machine with dirty cigarettes, they must be enjoying the food there.

Baobabs(猴面包树) are a symbol of Africa, and they are sometimes called "the tree of life", 【小题1】 Nine of the thirteen oldest trees, aged between 1,000 and 2,500 years, died in the early part of this century. Researchers say there have never been so many old trees dying in such a short time.

【小题2】 But they do not think baobabs across the continent of Africa are dying out. Baobabs will probably stop growing in some areas, and start growing in other areas.

Baobabs are often found in areas where elephants, rhinoceros(犀牛) and other wildlife live. 【小题3】

Baobabs take in lots of water during the rainy season and store (储存) it in: their trunks and branches. 【小题4】 Elephants can get water to drink from the trees.

Baobabs are also important to people. They use the baobab fruit to make drinks and mix with milk to create a kind of yogurt. 【小题5】 It's like a kind of medicine, and people can get energy from it. The leaves of the tree are used for making soup and it has some medical purposes.