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问题 解答题

一个底面周长是6.28厘米的直圆柱量杯盛有半杯水，当把一个铅球浸在杯里时，杯中水的高度由15厘米上升到17厘米，请问这个铅球的体积是多少？

答案

6.28÷3.14÷2=1（厘米），

3.14×12×（17-15），

=3.14×1×2，

=6.28（立方厘米），

答：这个铅球的体积是6.28立方厘米．

名词解释

分子病
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单项选择题

Proponents of organic farming claim that using chemical fertilizers and pesticides in farming is harmful to local wildlife. To produce the same amount of food, however, more land must be under cultivation when organic farming techniques are used than when chemicals are used. Therefore, organic farming leaves less land available as habitat for local wildlife.
Which one of the following is an assumption on which the author’s argument depends

A．Chemical fertilizers and pesticides pose no health threat to wildlife.

B．Wildlife living near farms where chemicals are used will not ingest any food or water containing those chemicals.

C．The only disadvantage to using chemicals in farming is their potential effect on wildlife.

D．The same crops are grown on organic farms as on farms where chemicals are used.

E．(E) Land cultivated by organic farming methods no longer constitutes a habitat for wildlife.
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