A

If we laid all of the blood vessels (血管) in the human body end to end, they would reach about 100,000km long. That's nearly two and a half times around Earth!

B

For the first time, Coca-Cola has showed that it uses 3,000,000 tons of plastic bottles each year. That's the weight of 15,000 blue whales-the largest animal on Earth.

C

If your throat tickles (发痒), pressing your ear might make it go away. That's because your throat and ears share the same group of nerves (神经). When you press your ear, the nerves in your throat can feel it.

D

It takes about 7 to 8 trees to make enough O₂ for one person to breathe for a year. Each person needs around 750kg of O₂ per year. A large tree might make around 100kg of O₂ per year.

E

To young children, a year might seem to last forever. But older people might say that it flies by. Why is that? According to the US scientists, young people's brains deal with information faster than older people. They take in more information and do more things in a day. So they feel like each day lasts longer. However, older people's brains take in less information and see a day pass more quickly.

F

About 200 muscles (肌肉) work together when you take a step. That's a lot of work for your muscles, since many people take about 10,000 steps a day. If you want to get some easy exercise, walking is good for you.