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【单选题】
How did the researchers ensu re that their findings are valid?A.
By attaching equal importance to all possible variables examined.
B.
By collecting as many typical samples as were necessary.
C.
By preventing them from being affected by factors not under study.
D.
By focusing on the family background of children being studied.
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皮皮学刷刷变学霸
举一反三
【简答题】露西的丈夫是一名编辑。
【简答题】什么是参考椭球定位
【单选题】已知某转轴在弯-扭符合应力状态下工作，其弯矩与转矩作用下的安全系数分别为=6.0，=1.8，则该转轴的实际安全系数值为 。
A.
12.0
B.
6.0
C.
5.69
D.
18.0