问题 单项选择题

设计科学探究的实验时,一般要()。

A.设置对照实验,设计单一实验变量

B.设计单一实验变量,其他因素不加控制

C.认真做好实验记录,并全部用图表表示出来

D.设计几十组实验.同时进行观察记录

答案

参考答案:A

解析:对照实验是指在研究一种条件对研究对象的影响时,所进行的除了这种条件不同之外,其他条件都相同的实验,其中不同的条件就是实验变量,设计原则是一个探究实验中只能有一个实验变量,其他因素均处于相同理想状态,这样便于排除因其他因素的存在而影响、干扰实验结果的可能.故选A。

完形填空
完形填空。
     We __1__ English, not learning about English. A student can __2__ all about English, but he __3__ not
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( ) 12. A. where          
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单项选择题