阅读理解
Have you ever been ill？ When you are ill, you must be unhappy because your body becomes hot,and there are pains all over your body. You don't want to work, you stay in bed,feeling very sad.
What makes us ill? It is germs（细菌）. Germs are everywhere. They arevery small and you can't find them with your eyes, but you can see them with amicroscope. They are very small and there could be hundreds of them on a verysmall thing.
Germs are always found in dirty water. When we look atdirty water under the microscope, we shall see them in it. So your father andmother will not let you drink dirty water.
Germs aren'tfound only in water. They are found in air and dust. If you cut your finger, ifsome of the dust from the floor goes into the cut（割开处）,some of the germs would go into your finger. Your finger wouldbecome big and red, and you will have much pain in it. Sometimes the germswould go into all of your body, and you would have pain everywhere.