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.

    Disney's princess stories are famous around the world. You must know some of them, such as Snow White, Cinderella and Sleeping Beauty.

    All princesses are very beautiful. Princes fall in love with them at first sight. In the end, the princess and prince have a happy life together.

    However, princesses often cannot protect themselves. They need help from others. This is the old image of Disney's princesses.

    A few weeks ago, Disney made 10 new rules. To be a princess, you must follow these rules. Surprisingly, no rule talks about having a "pretty face". Instead the rules are about good characteristics like honesty, loyalty and never giving up.

    Princesses need to grow up. When they meet problems, they need to protect themselves. They need to find ways to get away from dangerous people.

    For example, Elsa and Anna fight against the bad prince in Frozen. They need to believe in themselves and their friends. Mulan shows her courage to fight in the army. "Beauty" cannot help them. But a strong heart can. In the real world, these are the rules you need to follow.

    In 2014, Buzzfeed, a US news website, did a survey called "which Disney princess do you like most?". As it turned out, the most popular one was Belle ！More than 18 per cent of people chose her. Belie is in the movie Beauty and the Beast. She is very kind and gentle. She takes care of the Beast and uses her clever mind to get out of trouble.

    When you speak to foreigners, what will you do if you can't understand their languages? Will you use your body language to help you, or just say sorry to them and then go away? Learning spoken language is very important, but learning local gestures（手势） is also very necessary.

    I often use gestures to communicate with someone whose language I don't know. We use our hands to talk with each other. Although we don't understand the others' words, our hand movements make our conversation more necessary.

However, gestures aren't always clear. Different gestures may have different meanings in different countries and cultures.

    In many countries, people move their hands at someone to call him to come near. In the United States, people usually move hands at somebody with their palms（手掌） up and sometimes move just one finger. But in many countries in Asia, hand movements like that would be impolite. In Asia, many people move hands at someone with their palms down using all fingers.

    Do you use your thumb, your thick short finger to make gestures? In western countries, "thumbs-up" means agreement. But it is very rude in parts of Africa.

    If you want to say "OK" in America, you can make a circle with the thumb and the second finger. But in France, it means "zero", and it is very rude in many other countries.

    You can use your second finger to point at something but not at somebody in the United States. However, in some parts of Europe, Asia and Africa, pointing at anything with one's second finger is not polite.

    "V" form is often used when people take photos. But using two fingers to make up the "V" shape means "peace" in the West.

    The last example is that people in parts of Asia point to their noses to mean themselves, but people in western countries usually point to their chests.

    Gestures are important, but also have different meanings.

    About more than a hundred years ago，an American produced a game. He called it indoor tennis. The Americans were not interested in it at first but he sent it to his friends in London and it became very popular in Britain. The game was then played across dining-room tables，or on the floor with the net strung between two chairs. The balls were made of cork（软木）or rubber. The bats（球拍）were made of wood.

    A few years later a hollow ball like the one we use today was invented. The game then quickly spread all over the world. An Englishman once made a bat covered with rubber. He first sold the game in England and called it "Ping pong". "Ping" was the sound of the bat when it hit the ball, and" IPong" was the sound of the ball when it hit the table.