题干
Everyone likes living in a clean and comfortable environment. If the environment(环境) are bad， it will affect our body， and make us not feel well. Sometimes we may be terribly ill. At that time we don't want to work， and we have to stay in bed and rest at home. So the environment is very important to us.
It's germs(微生物) that makes us ill. There are germs everywhere. They are very small and you can't find them with your own eyes， but you can see them with a microscope（显微镜）They are very small and there may be hundreds of them on a very small thing， Germs can always be found in dirty water. When we look at dirty water under the microscope， we shall see them in it. Germs can also be found in air and dust（灰尘）. If you cut your finger， some of the dust from the floor may go into it， and you will have much pain in it. Sometimes the germs will go into all of your bodies， and you will have pain everywhere.
To keep us healthy， we should try our best to make our environment cleaner and tidier. This needs us to work together.
