使活性氮原子渗入零件表面的工艺称为（）A．氮化 B．氰化 C．离子氮化 D．软氮化

     The World Bank,the United Nations and the London School Of Hygiene and Tropica1 Medicine did a study
to urge hand-washing around the world. They found that one million lives could be saved each year if people
washed their hands with soap often. They said that programs to increase hand-washing with soap could be
among the most effective ways to reduce infectious disease.
      Doctors say,many diseases can be prevented from spreading by hand-washing. These include pinworms
(寄生虫),influenza (流行性感冒),the common cold,hepatitis (肝炎) A,meningitis ( 脑膜炎) and infectious
diarrhea.  (腹泻)
     Hand--washing destroys germs from other people,animals or objects a person has touched. When people
get bacteria on their hands,they can infect themselves by touching their eyes,nose or mouth. Then these people
can infect other people.
     The experts say the easiest way to catch a cold is to touch your nose or eyes after someone nearby has
sneezed or coughed.Another way to become sick is to eat food prepared by someone whose hands were not
clean. The experts say that hand--washing is especially important before and after preparing food,before eating
and after using the toilet. People should wash their hands after handling animals or animal waste,and after
cleaning a baby.
     The experts say it is also a good idea to wash your hands after handling money and after sneezing or
coughing. And it is important to wash your hands often when someone in your home is sick. The experts say
the most effective way to wash your hands is to rub them together while using soap and warm water.They say
you do not have to use special antibacterial soap. Be sure to rub all areas of the hands for about ten to fifteen
seconds. The rubbing action helps remove germs. Then rinse (冲洗) the hands with water and dry them.