【推荐1】Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing when you are happy.

Some scientists believe that birds sing some of the time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.

Do you know what a “territory” is? A territory is an area that an animal, usually the male, considers as its own. Only he and his family are welcome there. No other families are welcome. Your house is your territory where only your family and friends are welcome. If a stranger enters your territory and threaten (吓到) you, you might shout. Probably this would be enough to frighten him away.

If so, you have actually frightened the stranger away without having a fight with him. A bird does the same thing. But he expects an outsider almost any time, especially at nesting(筑巢) season. So he is screaming all the time, whether he can see an outsider or not. This screaming is what we call a bird’s song, and it is usually enough to keep an outsider away.

【推荐3】Weeks before Tomb-Sweeping Day（清明节）in April this year, hundreds of qingtuan were sold each day. The snack（零食）was still a must-have（必备品）for many people.

In the southern part of China, eating qingtuan at the beginning of spring is a kind of tradition for people. The Chinese began to eat it more than 2000 years ago. Making it really takes time and energy, and it is very delicious due to its softness, freshness and sweetness. The secret behind its mouth-watering（令人垂延的）taste is one of its materials—mugwort leaves（艾蒿叶）. The plant is mainly found in the Yangtze River Delta（长江三角洲）where it has perfect conditions to grow.

Now, qingtuan has already spread its special taste to the north of China. Li Yuan, a 30-year-old engineer who grew up in Zhejiang Province, brought qingtuan back to Beijing where he works. “It tastes different in and out of my hometown.” he said. “There’s no place like home.”

Qingtuan becomes more and more popular across the whole country. Even though there is warm weather and green leaves in spring, the season wouldn’t be complete without a taste of qingtuan. So it makes the start of the spring this year.

【推荐1】Artificial intelligence（人工智能） is set to help mankind in many ways. It will make everyone tasks easier and bring efficiency （ 效 率 ） to various industries. It might just prove to be one of man's greatest inventions.

And yet, like any other technology, AI will also bring risks. In February 2018, a group of AI experts got together to discuss the possible misuse of AI. What they found was the "Every AI advance by the good guys is an advance for the bad guys, too, " according to Quartz.

Their biggest worry was that criminals could use AI for wrongful purpose. One of the areas they looked at was the use of AI to create websites that could be used to steal people's personal information. Another possibility is that AI programs could be taught to hack（非法入侵） software and break into computer secure systems.

There are some other worries as well. It is possible that AI could be used to create fake images and videos. Then it will not be easy for people to tell which is the real one and which is the fake one.

Many leading figures in the technology world have expressed concern about AI. People like Bill Gates and Elon Musk have called for the industry to be more strictly regulated（规范）, as there are few laws right now on the use of AI.

In each “Opinion” section (部分) of The New York Times for Kids: China, we visit a different Chinese school and invite kids to express their opinions on a certain topic (话题). In March, we went to Shenzhen Bay School to record students’ opinions on how humans and AI (人工智能) get along.

Andy—15 years old

A huge difference between AI and humans is that robots don’t create new things and don’t get bored with things. Take the floor-cleaning robots as an example: They can sweep the floor for many years without getting bored, but we humans would get bored quite quickly. We instinctively (本能地) want to create new things, and that’s where we have an advantage over AI.

Eileen—13 years old

I want to add a pair of “super-long-distance” glasses (千里眼) in my eyes so that I can see interesting or dangerous things sooner. I could look out of the window and see people I miss far away. I could also predict earthquakes (预测地震). In this way, I can help warn (警告) people of the coming danger.

Eva—14 years old

I don’t want my memories to be changed or improved, because every memory is beautiful and worth recalling (值得回忆). But if it must be changed or improved, I would bring back all the memories I had as a baby that I’ve forgotten. My family are always happy whenever they talk about when I was a baby. I think they would be good memories, and I wish I could have them back.

Daming and Tony are talking about their school project. Tony has just made a model spaceship. But Daming hasn’t started it yet. Tony has heard the latest news. Scientists have sent a spaceship to Mars and it has arrived. But they haven’t discovered life on it. And no astronaut has been to Mars yet because it is very far away, much father than the moon. At last, Tony advises Daming to go online to search for information on space travel.

【推荐1】Grain Rain (谷雨) is the sixth of the Twenty-four Solar Terms in the traditional Chinese calendar, which falls on April 20 this year. As the last solar term in spring, this period sees the temperature rise and rainfall increase, creating a good environment for plants and animals.

Grain Rain is still linked with modern agriculture. It links grain with rain, reflecting an increasing amount of rainfall, which is good for the growth of crops. For farmers, it is a good time to sow.

It might not be so well-known that in Chinese tale an actual “grain rain” was recorded in the story of Cang Jie, who invented the first Chinese characters. Cang Jie created a set of characters from observing(观察)the tracks(足迹)of birds and mammals. After his great invention, grains started to pour down from the sky.

The Grain Rain Day has become a day to honor Cang Jie and the invention of the Chinese language and April 20 has been designated as the annual UN Chinese Language Day since 2010. Chinese characters are a treasure of the spiritual homeland of Chinese people, the thousands of years of Chinese culture, and an important symbol of cultural identity.

The main characteristic of a bird is feathers. No other animal has feathers. Other important features for birds are wings and hollow bones.

Birds fly by flapping their wings and using air pressure (压力)to create lift under their wings, Just like airplanes do. The peregrine falcon is one of the fastest birds. It can reach speeds of over 100 miles per hour when diving. Feathers are important to birds because they keep them warm, help them to fly, and provide camouflage(伪装). Hollow bones also help in flying because they help make the bird light enough to fly.

Although an important characteristic of frost birds is flying. Not all birds fly. Some birds that don't fly are penguins, kiwis and ostriches. Penguins actually spend much time in the water where they are swimmers. Ostriches on the other hand are very fast runners. An ostrich can outrun a horse!

There are all sizes of birds. Hummingbirds are some of the smallest birds, while ostriches are some of the biggest. Different types of birds eat different things. Some birds feed on plants, some birds eat insects and still others eat other animals like fish, snakes, mice or rats. Birds are also known for their migrating (迁徙) patterns to large groups. Some birds will travel long instances each season to stay in a climate that is good for their survival. Birds are sometimes kept as pets. The most popular birds for pets are tropical (热带的) birds like parrots. Birds also have a history of helping out humans in different tasks. They can carry messages(homing pigeons) and help hunt (falcons).

Read more facts about birds

An ostrich can run as fast as 43 miles per hour and grow as tall as 9 feet.

Blue birds can't see the color blue.

The hummingbird can fly backwards, but it can't walk.

The egg of a kiwi can weigh as much, as 20% of the mother's body weight.

【推荐1】The famous scientist and thinker, Charles Darwin, was born on February 12, 1809. As a boy, Charles liked to go for walks in the fields and forests. He enjoyed watching nature that includes plants and animals. He also liked collecting very much. He collected many things. At sixteen Darwin’s parents sent him to Edinburgh University to become a doctor. But he was interested in the history of nature. Then he went to study in Cambridge University. There he studied until 1831.

Some time later he wanted to be a scientist and studied the change of nature. So when a ship named Beagle left England in December, 1831, Darwin was on it. The trip lasted almost five years. In 1842, he went to live in Kent, and there he went on his studies of change in nature. By 1859 he had finished his famous book “The Origin of Species”（物种起源）. In 1871 he wrote another important book.

On March 14 in 2018, one of science’s brightest start went dark. Stephen Hawking, the world-famous British scientist, died at the age of 76 in Cambridge, UK.

Born in 1942, Hawking is considered by many to be the greatest scientist in history since Albert Einstein. He came up with the theory (理论) that the universe (宇宙) began with the Big Bang (大爆炸) and will end in black holes. His theories became the base for a lot of later research. He also wrote books to help people understand the universe. His most famous book is A Brief History of Time (《时间简史》), which has sold more than 10 million copies around the world.

Besides his scientific achievements, Hawking was also an inspiration to the whole world. When Hawking was 21, he was badly ill and it stopped him from walking and talking. Later in life, he had to sit in a wheelchair and “speak” using a computerized voice. But this didn’t stop him from living a meaningful and colorful life. “If one is physically disabled, one cannot afford to be psychologically (心理上) disabled as well,” he once said.

Hawking traveled around the world to attend science meetings. He even has millions of fans in China. In 1985, he took a train trip around China. In 2006, he was invited to speak at a physics meeting in Beijing. He was also a fan of pop culture and appeared on TV shows. In April 2016, he made a Sina Weibo account. His last post on Sina Weibo was written on Now 24, 2017. In the post, he answered two questions from Chinese pop star Wang Junkai.

Hawking may no longer be with us, but he will continue to inspire the world. He used to complain about his unfair life but then he felt pleased with what he had experienced. Just as he once said to himself, “Look up at the stars and not down at your feet.”