【问】 He then carried the mercury tube to the top of a mountain and observed that the columnfell steadily as the height increased，while another mercury column at the bottom of themountain remained steady (an example of another of the methods of science，the con-trolled experiment). (A Course in Basic Scientific English，P. 13)

[原译]于是他把水银柱管带到山顶上并观察到水银柱随着高度的升高而恒定降低，而另一个在山下的水银柱则保持不变(这是科学的方法另一例证，对照试验)。(中译本)

请问the controlled experiment是哪个成份的同位语?

【答】 根据上下文可以看出，the controlled experiment并不是an example的同位语，而是an-other of the methods of science的同位语。

[试译]……(这是另一种科学方法即对比实验的一个实例)。