Every time you move, three body systems work together to help you. Your skeletal（骨骼的）system works with your muscular（肌肉的）and nervous（神经的）systems to help you run, jump, sit, walk, and swim.

Your skeletal system has more than 200 bones. It is a structure that supports your body and protects your inner body parts. Even though the bones are hard, they are still living tissues（组织）.

Your muscular system is made up of all the muscles in your body. Your skeleton could not move without muscles. You also need your muscular system to keep your posture.

The nervous system is the control centre for all of your body’s organ（器官）systems. It helps you to know the changes in you and around you. It helps you to react（反应）to your environment.

All of your muscle movements（运动）are controlled by your nervous system. The brain is the centre of your nervous system. Billions of nerve cells（细胞）make up the tissues of your brain. Each day, nerve cells in your brain send and get thousands of messages to and from the parts of your body. Of course, nerve cells are found throughout the body, not only in the brain according to the knowledge you have learned in biology.

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The United Nations (UN) is an international organization that allows all the countries in the world to meet and work together. The UN was founded in 1945 after World War II. Now almost every country in the world is a member. There are 193 members in all.

The UN was founded with five main goals:

● To help keep the peace

● To protect human rights

● To bring aid to people who need it

● To help countries develop

● To make sure international laws are followed

The UN is a parent group. It leads many organizations in different areas. Below is a list of just a few of the organizations.

In recent months, the UN’S WHO has been helping keep the world safe by studying and reporting on COVID-19.

Should you see a doctor every time you’re sick? Of course not! Doctors don’t have a cure (疗法) for everything. In fact, there are many simple illnesses that are difficult for doctors to cure. Sometimes people use different “home remedies (治疗法)” for them.

The cold virus (病毒) is one example. People in many countries don’t take medicine for a cold. They make a big pot of hot chicken soup instead. They eat the soup and rest. Many people believe that chicken soup is a natural and healthy cure for a cold. And in fact it really helps: drinking a lot of water is good when you have a cold. Also, the hot soup helps you breathe better and helps your throat.

And in China, it’s common to cure a headache with an egg. You boil the egg, take off the shell and rub (揉) the egg on your face, head and neck until the egg becomes cool. Some people think this helps you sleep better, too. Rubbing with the egg relaxes you. Often headaches are because of stress, so relaxing is a great idea.

What about a fever? There are a lot of different home remedies, but an interesting home remedy uses vinegar (醋). In Russia, people rub it into the skin. Vinegar makes your skin feel cooler, and it can help lower your body temperature a little.

One of the world’s oldest home remedies is tea. You can use herbal (草药) teas for all kinds of simple stomachaches and sore throats. Some popular ingredients in home remedy teas make a sore throat feel better and help you relax.

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