Waste sorting (垃圾分类) has come. It’s so important to us humans. We do waste sorting before throwing rubbish away. We are happy to see some fine examples. However, it is not easy for everyone to do this. Some people may spend so much time deciding the kind of the rubbish. Luckily, the twin sisters front Beijing developed an app (应用程序) to help solve the problem.

The app is easy. When users need to throw away their rubbish, they open the app first. In the app, they can find the names of different rubbish. Then, they choose a kind of rubbish in the app, and the right rubbish bin (箱) will open. The app is also helpful. It makes use of speech recognition (语音识别) technology. Then users can just speak out the name of the rubbish, and the rubbish bin will open.

In fact, waste sorting isn’t difficult, but we need some time to get used to it. Of course, technology can help us to do it better.

【推荐2】Sometimes we throw apple remains into forests, hoping small animals around may find them. But what if they are never noticed? People believe they would rot (腐烂) one day, so it doesn't matter. Is that true?

Sure they will. But it won't happen overnight.

Marjorie Woodruff, who works in the Grand Canyon, set up a small experiment. She put a banana peel, orange peels in a box, wide enough to allow small animals to go in and out. After six months, the orange peels had dried out, the banana had turned black. Nothing had been eaten or had rotted.

She buried the same things in sand and soil and six months later everything could still be seen.

In fact, it takes two months for apple remains to rot and an orange peel can take up to one year.

“Do we eat orange peels? We do not. So why would a squirrel eat?” Woodruff writes in High Country News. “The animals do just fine on nuts and berries. They do not need us. ”

There’s another point to think about.

When animals start to get food from people, they may stop looking for their own food in nature. This is dangerous because it may weaken their hunting ability.

Food waste also attracts animals to areas where there are a lot of people, says the Leave No Trace organization. This may put their life in danger as they may get used to looking for food alongside busy roads. Many of them are too small to be noticed by drivers.

When you're throwing fruit remains, you may be fined (罚款). Fines are different. Some states might only fine people $100, but a few states fine people more than $6,000 for the first time.

People have been using the wind’s energy for a long, long time. More than 5, 000 years ago, ancient Egyptians made boats powered by the wind. In 200 B.C., people used windmills (风车) in China.

Today, we collect the wind’s energy with wind turbines (润轮). A turbine is similar to a windmill. It is a very tall tower with two or three blades (叶片) at the top. These blades are turned by the wind. The blades turn a generator (发电机) located inside the tower, which creates power.

Groups of wind turbines are known as wind farms. Wind farms can be found near farmland, in narrow mountain passes, and even in the ocean, where there are stronger winds. Wind farms create power for nearby homes, schools and other buildings.

In places like the Midwest and along coasts, winds can provide cheap power. Another great advantage (优点) of wind power is that it is a clean form of energy. Wind turbines do not burn oil or coal and do not pollute the air.

Wind is not always an ideal source of energy, however. Wind speed changes from time to time, depending on the time of day, weather and location. Wind turbines can be also dangerous for bats and birds. These animals cannot always tell how fast the blades are moving and crash into them.

Stanford is a world-famous university on the west coast of the U.S. It was built by Stanford and his wife in memory of their only son who died of a strange disease.

Tourists are often surprised at the beauty of Stanford. Among the green trees, buildings with yellow walls and red tops make up a beautiful picture. Many tourists wonder why yellow and red were chosen. That’s because they were the favorites of Mrs. Stanford.

The Big Church is the most important building in Stanford. It stands at the center. It was built by Mrs. Stanford to remember her husband who devoted (贡献) himself to the university. There, students and teachers can communicate with God and hold great activities, such as concerts and celebrations.

The tallest building in Stanford is Hoover Tower, which is the landmark of the university. A man named Hoover had done a lot for the university. The things he once used can be seen on the first floor. On the top of the tower, tourists can have a good look at the whole campus (校园).

As one of the world top universities, Stanford has many subjects that stand among the top ones in the world. And computer science has been the first for many years. If you want to study computer in a university abroad, maybe it is your best choice.