◎ 题干
阅读理解。
A. Causes of overusing fluoride ( 氟化物 )
B. Negative effects of fluoride
C. Safe use of fluoride
D. The expert's background information
E. No need to worry about fluoride poisoning
F. Solutions to improper use of fluoride
     I have heard that fluoride can help stop dental decay, but I recently read that it is poisonous. Which of
these is true? How can children use fluoride safely?
1. (     )
     This question is answered by Dr Marcia M. Rich who practises general dentistry in Newholt. She is also
a lecturer at the University and a writer for the monthly magazine Your Dentist Cares.
2. (     )
     My answer to the first question is to stress that fluoride works well and is safe when users follow
instructions. Young children have a tendency to swallow toothpaste, which is why they should only have a
tiny amount of fluoride toothpaste on their toothbrush. If this simple measure is taken, parents can be
confident that children will be protected against tooth decay, and come to no harm.
3. (     ) 
      Almost all medicines have a negative effect-or even be deadly-if they are not taken as directed. So you
are right-fluoride can be poisonous if it is swallowed in very large quantities. It is for the reason that fluoride
supplements can only be obtained on prescription from the doctor or dentist. Please be assured that fluoride
overdoses are rare-in fact, I have never heard of any fatal incidents related to fluoride poisoning.
4. (     )
     Scientific studies have shown that fluoride can help to prevent cavities(牙洞) as long as it is used
correctly. If fluoride is abused, there is a risk of illness or even deaths in extreme cases. If a deadly amount
of fluoride is taken, immediate first-aid could save a life. A person who has swallowed a large amount of
fluoride will probably start vomiting. If not, the patient should be given milk or antacid and taken to the
nearest hospital for emergency treatment.
5. (     )
     Taking too much fluoride while teeth are growing can lead to a condition called dental fluorosis. The most
likely cause is the swallowing of fluoride toothpastes by young children. It can also be caused by inappropriate
use of fluoride drop or other fluoride supplements, for example when fluoride is already present in drinking
water.
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◎ 知识点
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