Getting electricity has always been a problem for the 173 people living in Nuevo Saposoa, a small village in Peru, South America. However, things went from bad to worse in March 2015 after heavy rains damaged the only power cables in the area. The villagers were forced to use oil lamps, which are not only expensive but also dangerous because of the harmful gases they produce.

    Luckily, researchers at the University of Technology (UT) in Lima, Peru heard about their problem and found a wonderful solution. They made a lamp that can be powered by plants and soil, both of which can be easily found in the Amazonian rainforest where the village lies. The lamp takes energy from a plant growing in a wooden box and uses it to light up an LED light bulb.

While that may sound amazing and even impossible, the science behind the ides is quite simple. As plants create their food (using the sun's energy, water and chemicals from the soil), they also produce waste which they return to the soil. Tiny animals in the soil eat this waste and they produce electrons – the building blocks of electrical energy. The UT team put special sticks inside the soil to capture the energy and keep it in the lamp's batteries for later use. The researchers say a single charge can power a 50-watt Led light for two hours - enough time for local villagers to get their evening work done.

The university gave ten Plant Lamps to the villagers of Nuevo Saposoa in October 2015. So far, they have been a huge success! Elmer Ramirez, the UT professor who invented the lamp, believes the Plant Lamp could help improve the lives of many people, especially small rainforest communities, 42% of whom have no electricity.

    The crow （乌鸦） is an ordinary （普通的） bird. It is about twenty inches （英寸） long and black all over. Crows are dirty birds because they live on old bad food. Crows eat a lot of waste food. In this way they are more useful to us than any other bird. They clean up the dirty things in our streets. Crows are always hungry. They look for food all day long, and in the evening you can see them in large numbers flying back to their nests (窝) in the trees. They sleep there at night. Crows are much noisier than other birds. Very often a large number of crows will get together on one house and talk. Sometimes they talk together, and sometimes they do it by talking like human beings (人类). It is easy to tell from(区别) crows' sounds whether they are pleased or angry. Perhaps crows talk a lot because they are friendly birds. A pair of crows will live together all their lives, and if one of them dies, the other one becomes very sad and quiet for the rest of its life and sometimes it dies, too.

    One of the hottest places on the earth is Death Valley. It's a desert valley in North America. The animals in Death Valley don't use technology to keep cool. They have special abilities that help them live there.

    The kangaroo rat is one animal that lives in Death Valley. During the day in Death Valley, it gets hotter than 100°F. The kangaroo rat rests all day in a hole in the ground. It covers the hole with grass to keep out the heat. The kangaroo rat comes out at night when it is cooler. This little rat is also very good at conserving (节约) water. It gets all the water it needs from the food it eats. Some kangaroo rats never take a drink of water in their whole lives!

    The sun makes the desert sand very hot. Animals, like snakes, get too hot if they lie on the hot sand too long. One snake, called the sidewinder, can solve this problem. When it travels, the sidewinder bends (使弯曲) its body into a“W”shape. Then it uses the bottom (底部的) parts of the“W”like legs and walks sideways (向一侧). That way it touches only a little of the sand at a time, so the hot sand doesn't burn the snake. This strange way of moving is how the sidewinder got its name.

    A lot of water in the desert is too salty for most animals to drink. All water has some salt in it. As the desert heat dries up pools of water, the salt is left behind. The remaining water in these pools can be much saltier than the ocean. One kind of fish, the desert pupfish, can live in these salty pools because it can drink the salt water.

    What was discovered by accident? The answer is penicillin(青霉素). It kills germs. By killing germs, it saves lives. Suppose you are sick. You go to a doctor. She examines you. She says you have a "staph" infection(葡萄球菌感染). She gives you some medicine. You take it. The medicine knocks out the staph. Soon you are well. Before penicillin, this would not happen. Staph was almost sure death.

    Everyone wanted a medicine. Laboratories worked day and night. They grew the staph in small dishes. Then they tried to kill it. Nothing worked.

    The laboratory dishes had covers on them. They kept things from falling into dishes. Molds(霉菌)were a big worry. They are always in the air. You can't see them. They're too small .There are thousands of different molds. Molds can make an experiment (实验)fail. That's why dishes are covered.

    Dr. Alexander Fleming was working to kill the staph germ. He worked for years. One day he took a cover off a dish. He looked inside. There was a thick growth of staph germ. There was also some mold. Then he saw something strange. Where the mold was, there was no growth of staph. This is what Fleming probably thought. "By accident, I found a mold to kill the dreaded staph."

    This is how penicillin was found. But here's the real miracle(奇迹). There are thousands of kinds of molds. But only one kind can kill staph. The mold must have fallen into the dish a few days before. The cover was probably off only a few seconds(秒). In those few seconds the right mold fell into the right dish. Another mall might have thrown the dish away. But Fleming was very careful and smart. He understood what the mold did. How lucky the humans were!