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问题 选择题

（09兰州）LiFePO4新型锂离子动力电池以其独特的优势成为奥运会绿色能源的新宠，已知P的化合价为+5价，则LiFePO4中Fe的化合价为  （  ）

A．+1

B．+2

C．+3

D．+4

答案

答案：B

① 考查重点：化学式与化合价② 解题思路：在化合物中，正负化合价代数和为零，设Fe元素的化合价为？ +1+？+（+5）+（-2）×4="0            " ？=" " +2

填空题

元代是（）发展鼎盛的时期，出现了关汉卿等一批杰出的剧作家，产生了大量优秀戏曲作品。
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问答题

The eighteenth-century British thinker Edmund Burke made the following observation about the benefits of opposition: "He that wrestles with us strengthens our nerves and sharpens our skill. Our antagonist is our helper."
In your view, to what extent can we benefit from opposition to our ideas, or desires. Write an essay of about 400 words that defends challenges, or qualifies Burke’s statement about the benefits of opposition. You should present your argument with reasons and examples.
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