We do not know when people invented wheels. But once it was invented, knowledge of the wheelquickly across the world. It is easy to move things with wheels. The first example of wheels dated from about 3. 500 to 3. 000 BC. The cart or wagon was the first vehicle which had wheels. At that time, they were pulled by humans or animals. Today, there are still carts drawn by animals in many countries. These carts are mainly used to move things orpeople. Around 2, 000 BC, the chariot(双轮敝篷马车)appeared. It moved even faster than the cart, so it soon became an importantin the war and later was introduced to other ancient countries, such as Egypt, Persia, Greece and Rome.

    The invention of wheels is very important to theof new transportations. Without wheels, the invention of bicycles, motorcycles, cars, trains, and planes may not be possible.