题目
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答案
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解析
核心考点
举一反三
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若多次投放,则某一时刻水中的药剂浓度为每次投放的药剂在相应时刻所释放的浓度之和.根据经验,当水中药剂的浓度不低于4(克/升)时,它才能起到有效治污的作用.
(1)若一次投放4个单位的药剂,则有效治污时间可达几天?
(2)若第一次投放2个单位的药剂,6天后再投放
![](http://img.shitiku.com.cn/uploads/allimg/20200205/20200205062901-13993.png)
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A.(-2,-1) | B.(-1,0) | C.(1,2) | D.(0,1) |
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A.![]() | B.![]() |
C.![]() | D.![]() |
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A.1 | B.2 | C.3 | D.4 |
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