Whitewater rafting (漂流) is an exciting sport and, despite how it looks, you don't need to be incredibly brave or technically skilled to enjoy it. Here's everything you need to know about whitewater rafting.

River Grading System

The first thing you need to know is about the grading system. In general, beginners and older children will be safest and most comfortable on Grade II and III rapids. Those with more experience or advanced river skills can cope with Grade IV and V rapids.

Key Terms to Know

Your whitewater rafting guide will brief you before you hit the river and will run through the key terms and instructions they'll likely use. Here are some of the most important that you will hear:

Put in: The starting point of a rafting trip.

Take out: The ending point of a rafting trip.

Swimmer: Anyone who falls out of the raft is called a swimmer. Your guide might shout "swimmer!" to get that person's attention when attempting a rescue, as they're unlikely to know every passenger's name.

Safety Tips

The most important safety tip is always to follow your guide's instructions. They are trained to keep you safe during what can be quite a risky activity to the untrained. Avoid taking valuables on a rafting trip, including cameras, unless you have a dry bag.

What to Wear

Tour companies will provide you with the essential equipment, including paddles, life jackets, and helmets. Your clothing is up to you, but you'll be expected to wear suitable shoes. Cotton clothing isn't a great idea because it is cold when wet.

The topic of "crossing your legs" has been hotly discussed on the Internet recently. The truth is that crossing one leg over the other, a common sitting posture preferred by many people, may actually do harm to one's health. So while seated, try not to do so any more.

Whether it is at the office, in a waiting room or relaxing at home, many people' s go-to posture is one leg over the other, crossed at the knee. If you're like many of us, you spend too many hours of your day seated and for most of that time, you have crossed your legs for comfort.

One study found that people who sat with their legs crossed for more than three hours a day were more likely to lean forward and to round their shoulders. But the research relied on people's own estimations of how long they crossed their legs for.

When you cross your legs, you are putting compression and pressure on your leg and knee joints and nerves. The way you sit is a huge determinant of your health and the way your body moves and functions. Sitting with your legs crossed leaves your hips uneven and forces your pelvic bone (盆骨) to rotate. Therefore, the longer you sit in this uneven position, the more pressure is placed on your knee and spine (脊柱), increasing the likelihood that it will develop into a long-term issue.

If seated long, then more importantly for you, cultivate and develop a healthy habit of sitting position. And here are the followings. Switch sitting positions often. Take brief walks around your office or home. Gently stretch your muscles every so often to help relieve muscle tension. Keep your feet on the floor, with your ankles in front of your knees. Relax your shoulders; they should not be rounded. Keep your elbows in close to your body and let them be bent between 90 and 120 degrees. Make sure that your back, thighs and hips are fully supported. Try doing those and maybe some of them fit you.

Roosters (公鸡) act differently when faced with another chicken rather than just their own reflection. This may mean that the birds can recognize themselves in a mirror, a key indicator of self-awareness. In the traditional mirror self-recognition test, which originated in 1970, researchers place a mark on an animal's body in a spot that it only see when seeing its reflection. They note if the animal touches the mark while examining its mirror image, which suggests it understands that what it sees represents its own body. Few non-human species have passed this test, but they include some great apes, dolphins, elephants.

However, results from the test are often variable. Sonja Hillemacher and her colleagues from the University of Bonn in Germany wondered if this was because there is little natural reason for many animals to find out such marks. So, they have tried to adapt the test to the natural behaviour of roosters. Roosters usually make loud noises to warn other chickens when they see predators (捕食者) but generally stay quiet when they are alone. 

In the lab, they tested 68 roosters one by one in an arena divided by a wire net. They placed a bird on one side, and either left the other side empty or put another rooster in it. Then they added a mirror to the divider for some tests. The results showed that when a rooster was paired with another rooster, it raised the alarm more often than when it was alone, regardless of whether it could see its own reflection. When another rooster was present but hidden behind a mirror, few alarms were raised, showing that roosters can distinguish between reflection and reality through vision rather than smell or sound.

Since the birds acted similarly when alone and with a reflection, they may realise their reflection is of themselves, say the researchers. While the research suggests that roosters may recognize themselves in mirrors, it is too early to claim that chickens possess this ability.