题干

某研究性学习小组就“不同水质对蛙卵孵化的影响”进行了探究,其实验记录如下表:

       组别

项目

水质

水量

水温

蛙卵数

孵出的蝌蚪数

    A组

河水

500毫升

22℃

30个

28只

B组

蒸馏水

500毫升

10℃

30个

9只

该实验设计的不妥之处是(     )

A:没有对照实验

B:水量过多

C:水温不一致

D:水中没有水草

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C

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