Did you ever wonder how some of your favorite foods, products or toys came about? Believe it or not, they may have been an accident, or a failure of some other intention. Below, we found three mistakes we're thankful for turned out to be what they are.

1. Most historians hold that the Chinese invented fireworks in the 9^th century when they discovered how to make gunpowder. Story has it that a Chinese cook accidentally mixed together what were then considered common kitchen items and noticed they burnt. When put tightly in a bamboo tube and lit, it blew up.

2. In May of 1886, a law led John Pemberton, a pharmacist(药剂师), to rewrite the formula(配方) for "Pemberton's French Wine Coca", his popular headache treatment. Containing sugar instead of wine as a sweetener, the outcome became something for Coke, which was later mixed with carbonated(碳酸) water. His bookkeeper suggested the name Coca-Cola because he thought the two C's would look good together, which is how what we call Coca-Cola, a world-wide drink came into being.

3. During World WarⅡ, scientists at the University of Birmingham invented the magnetron(磁控管)—an important heat-producing part of the microwave oven. While working for Raytheon Corporation after the war, the American engineer Percy Spencer was testing the magnetron when a chocolate bar in his pocket melted. He went on to test other foods including popcorn kernels(仁), and found it to be a much more efficient way to cook. In 1947 Raytheon came out with the first restaurant microwave oven, which was six feet tall and weighed 750 lbs.

    The 2017 Fortune Global Forum (财富全球论坛) was held in Guangzhou from December 6 to 8, 2017 for the first time with the theme of "Openness and Innovation: Shaping the Global Economy". This is the fifth Fortune Global Forum held in China. Since its beginning in 1995, the Fortune Global Forum has been providing chances for CEOs of the world's most important companies and world leaders to get together and discuss matters about international business.

    There are several reasons why Guangzhou was chosen as the host city for the 2017 Fortune Global Forum. First, Guangzhou is the capital of Guangdong Province which is historically an active centre for free trade. Guangdong Province is also the most populous (人口稠密的) province in China with a population of 110 million, bigger than that of any other province in China. What's more, more than half of the Fortune Global 500 companies have already set up branch offices (分公司) in Guangzhou.

    Hosting the 2017 Fortune Global Forum also brings benefits to Guangzhou. First, it will help change the city into a high-level technology centre in the future. Moreover, it will attract more companies to invest and develop in Guangzhou and Guangzhou can take the chance to encourage local companies to go global and deepen cooperation with companies from all over the world.

    Great effort was made in order to make the event a success. For example, a total of 1,200 volunteers were chosen mostly from universities to serve the 2017 Fortune Global Forum. Training courses were also carried out to prepare volunteers for their jobs. They even had a volunteer's song. The lyrics and music of the song was written by the famous lyricist Zhong Shan and composer Wang Xiaosong. The official version of the song was sung by famous singers Wang Chenrui and Wang Sulong.

A cloud is made of water drops or ice crystals (晶体) floating in the sky. There are many kinds of clouds. Clouds are an important part of Earth's weather.

How do clouds form?

The sky can be full of water. But most of the time you can't see the water. {#blank#}1{#/blank#}They have turned into water vapor (蒸气). As the water vapor goes higher in the sky, the air gets cooler. The cooler air causes the water drops to start to stick to things like bits of ice or sea salt and so on.

What are some types of clouds?

{#blank#}2{#/blank#}One way is by where they are in the sky. Some clouds are high up in the sky. Low clouds form closer to Earth's surface(表层). In fact, low clouds can even touch the ground. These clouds are called fog. Middle clouds are between low and high clouds. The other way to name clouds is by their shape. Cirrus clouds (卷云) are high clouds. They look like feathers (羽毛). Cumulus clouds (积云)are middle clouds.{#blank#}3{#/blank#}Stratus clouds(层云)are low clouds. They cover the sky like bed sheets (床单).

What causes rain?

Most of the water in clouds is in very small water drops. The drops are so light that they float in the air. Sometimes those drops join with other drops.{#blank#}4{#/blank#}When that happens, gravity (重力) causes them to fall to Earth. We call the falling water drops "rain". When the air is colder, the water may become snow.

 Why do you think scientist study the clouds? (回答不多于8个单词)

{#blank#}5{#/blank#}

ChatGPT is a new clever robot. It can understand languages and talk to people, too. When you talk with ChatGPT, it can answer different kinds of questions, such as questions about history and science. It's so clever that it can reuse your questions !

 In different situations (情况), ChatGPT can be serious or funny. For example, if you say, " Tell me a lie, " ChatGPT might say, " The sky is green. " Then, if you say, " That's not a good lie. Tell me more lies, " ChatGPT might say, " In fact, I am a human. "

ChatGPT can also write passages and stories. Maybe one day, it could even work as an engineer. But some scientists think that ChatGPT might not always be a good thing. For example, a lot of American college students do homework with the help of ChatGPT. Elon Musk, the person behind it, says "ChatGPT is strong but also a little dangerous. " So we must use ChatGPT carefully. 

It's time to put down your phone.

Researchers from a university in California have found that eye damage caused by too much screen time can harm other important organs(器官) and even shorten your life. Professor Pankaj Kapahi and Brian Hodge published their findings. It showed that the real situation is worse than we thought.

"Our study shows that this is a big problem: eye damage may actually lead to problems in other organs,"Kapahi said. He and Hodge studied the patterns of fruit flies and found that overexposure(过度接触) to light in the eyes can cause or worsen chronic disease(慢性病). Further research found that fruit flies that were completely indarkness lived longer than those that were not.

Too much time spent in front of a screen can harm your health. "To our surprise, we found that the eye itself, at least in the fruit fly, can directly change life," Hodge said. "Looking at computer and phone screens will surely do harm to us. On top of these, being exposed to light pollution late into the night is especially bad for us Kapahi explained. "It_messes up eye protection, damaging the rest of the body and the brain.

These findings are very worrying because screen time has increased fast for many kids because of COVID-19. Parents reported that although they prevented their kids from playing video games, children's screen time still increased from 0.75 hours to 6.5 hours a day due to online classes. 

"We always think of the eye as something that serves us. We don't think of it as something that needs to be protected,"Kapahi reminded us.