[单项选择]

Lead Poisoning: A Silent Epidemic

How much lead is harmful Until the 1970s, exposure to lead was considered dangerous only at blood levels associated with extreme symptoms of poisoning: convulsions (惊厥), brains swelling, acute kidney disease, stomach pains and hallucinations (幻觉). But low -level lead poisoning can cause symptoms that, while subtle, are no less serious. As a result, the CDC has continually lowered the point at which patients should be treated for lead poisoning.
One of the most influential study of lead’ s low - level effects was published by Herbert Needleman, professor of psychiatry at the University of Pittsburgh Medical School. Testing first and second grade students in the Boston area, he found the lowest I. Q. , academic achievement, language skills and attention span among children with the highest tooth levels (起损害作用的量) of lead. "None of their lead levels exceed the CDC’s 1979 toxicity threshold. "Says Paul Mu
A. the amount of exposure was large.
B. it caused extreme symptoms of poisoning.
C. it caused symptoms whether serious or not.
D. poisoning had led to death among the poisone

[单项选择]
How much lead is harmful Until the 1970s, exposure to lead was considered dangerous only at blood levels associated with extreme symptoms of poisoning: convulsions (惊厥), brains swelling, acute kidney disease, stomach pains and hallucinations (幻觉). But low -level lead poisoning can cause symptoms that, while subtle, are no less serious. As a result, the CDC has continually lowered the point at which patients should be treated for lead poisoning.
One of the most influential study of lead’ s low - level effects was published by Herbert Needleman, professor of psychiatry at the University of Pittsburgh Medical School. Testing first and second grade students in the Boston area, he found the lowest I. Q. , academic achievement, language skills and attention span among children with the highest tooth levels (起损害作用的量) of lead. "None of their lead levels exceed the CDC’s 1979 toxicity threshold. "Says Paul Mu
A. It tested first and second grade students from all over the United States.
B. All the students tested had lowerI. Q. and academic achievement than normal students.
C. None of the students with symptoms exceeded the safety level set in 1979 by CDC.
D. It proved the lead’ s high - level effects on people, especially on children.

[填空题]Silent Spring contained so much carefully collected scientific evidence that it was widely acclaimed as a significant book when it came out in the early 1960s.

[填空题]We will lead a much easier life in the future.

[简答题]How much there is to learn and how much I don’t yet know is one of the most important things I’ve learned. (periodic sentence)

[单项选择]How much is the discount

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A. 100 dollars,
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C. 25 dollars.
D. 20 dollars.

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C. Fifteen dollars.

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A. Three dollars.
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