Six children were in the hospital.They were very sick，but the doctors didn't know what to do.They called Dr.Richard Besser，an expert on strange illnesses.
   First，Dr.Besser needed to find the cause of the illness.He looked for germs（細菌） in the children's bodies carefully.In every child，Dr.Besser found the same kind of the bacteria（病毒）E.coli.He then looked at the bacteria's DNA.It showed him that this kind of E.coli was dangerous.He knew that the bacteria can get into the body through mouth，nose，eyes or a cut in the skin，which may do harm to our immunity（免疫力），causing different kinds of illnesses like fever，headache and stomachache.
   Dr.Besser knew E.coli could move from animals to humans.Had the children touched animals that carried the bacteria？Besser found other E.coli cases in the area where the children lived.But it wasn't enough.Dr.Besser then made a list of what the sick children had eaten.They had all eaten cheese，apple juice and fish.He then made a list of what healthy children in the area had eaten.They had eaten the cheese and fish，but not the apple juice.
   Besser went to where the apple juice was made.He saw animals around the apple trees.He also saw the workers using dirty apples that had fallen on the ground.More importantly，he saw that the apples were not washed before the juice was made，and that the juice was not heated.Doing these things would kill the bacteria.Besser then knew it was the apple juice that made the children sick.
   So he treated the children with medicine who were less serious.Those who were more serious required several days' hospital stay.One or two weeks later，the children got better.And what Besser learned that day now helps keep others safe.

	Possible danger of the infection（感染）	It may get into the body through different parts of the body.It's so（1） harmful harmful to the body that it may cause fever，headache and stomachache.
		Animals were around the apple trees. The workers used dirty apples to make apple juice without washing. The apple juice was not heated.
	Process of Dr.Besser's discovery	He（2） checked checked the children's bodies and found out the bacteria--E.coli. He found other E.coli cases in the area where the children lived. He （3） compared compared the food the sick children had eaten（4） with with that the healthy children had eaten.
	Treatment Dr.Besser gave to the children	-For the less serious：Have some medicine. -For the more serious：（5） Stay hospital Stay hospital for days.