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下图是我们研究常见物质组成、性质的几个实验： ①实验1：写出该反应的化学方程式 。 ②实验2：该实验证明 组成的化合物。 ③CO 2 与NaOH溶液反应无明显现象，为证明其反应，设计实验3。可观察到的实验现象是塑料瓶变瘪了，其原理是利用 。有同学却对此提出质疑，他认为上述实验不严谨，其理由是 ，要得到科学严谨的结论，仍利用该装置，补做的对比实验是将氢氧化钠溶液换成 ，与加入氢氧化钠溶液的实验现象进行对比。 若用检验生成物的方法证明二氧化碳与氢氧化钠发生反应，所用的试剂是 。
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举一反三
【单选题】In an attempt to improve the overall performance of clerical workers, many companies have introduced com- puterized performance monitoring and control systems (CPMCS) that record and report a worker’s...
A.
That workers with the highest productivity would also be the most accurate
B.
That workers who initially achieved high productivity ratings would continue to do so consistently
C.
That the highest performance ratings would be achieved by workers with the highest productivity
D.
That the most productive workers would be those whose supervisors claimed to value productivity
E.
That supervisors who claimed to value productivity would place equal value on customer satisfaction
【简答题】指沿垂直杆长度方向的截面,轴线是指各截面的形心的连线,两者具有相互垂直的关系。