过去式是用来指出过去会发生或存在,然而现在已不再发生或存在的事物。 当研究报告的作者想要描述过去所做过的实验时(在研究报告的章节里),就可以用过去式。例如:
To test the model, we ran a series of simulations．
The samples were then placed in the test chamber and the temperature was increased．
当作者在叙述实验的结果时,可以用过去式来表达:
When water was added to the solution, the deposition rate increased．
Our method found the solution faster than Wheaton’s method in nine of ten trial．
当作者想叙述其他研究人员的发现时(例如,在研究报告中的文献回顾部分),也可以用过去式来表达。 例如:
Johnson (1987) found that raising the temperature of the substrate increased the deposition rate．
Stewart (1974) was the first to study this phenomenon． He reported that it occurred throughout the population．(www.xing528.com)
如果句子中提到过去的某个特定的时间,那么当然要用过去式来表达。 例如:
Professor Li returned to China from the United States in 1989．
Our company began manufacturing the new memory chip last month．
在科技研究报告中,有时候作者也会用过去进行式。 例如:
As the solution was being stirred, silica powder was gradually added to it．
不过,一般来说,不需要用过去进行式,只要用简单过去式就足够了:
As the solution was stirred, silica powder was gradually added to it．
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