When you are ill, you must be unhappy because you feel uncomfortable, you don't want to work and you may have to stay in bed. This makes you feel very sad.
What makes us ill? They are germs. Germs are everywhere. They are very small and you can't find them with your eyes. But you can see them with a microscope(显微镜). They are very, very small and there could be hundreds of them on a little piece of something.
Germs are always found in dirty water. When we look at dirty water under the microscope. We will see a lots of them in it, so your father and mother will not let you drink dirty water.
Germs are not only found in water. They are found in air and dust(灰尘), if you get a cut in the finger, and if some of the dust from the floor goes into the cut, germs will come into your finger. Your finger will become big and red, and you will have much pain in it. Sometimes if the germs go into all of your body, you may have pain in every part of the body.
What can you do to fight germs? You should wash your hands with soap and water. Soap kills many germs, and water washes them away.
