例如：Many of the lakes and wetlands in the region are located in craters or valleys blocked by early Pliocene lava flows (Ollier Joyce, 1964).
Garcia (1993) suggested that under certain conditions, an individual’s deposit income is the same as the income from purchased national debt, thus changes in the amount of bank loans and deposits caused by changes in the amount of reserves will eventually affect the bond price.
需要注意的是如果引用的是一些已经过时或失效的科研结果，动词要使用过去时。
例如：Nineteenth-century physicians held that women got migraines because they were "the weaker sex," but current research shows that the causes of migraine are unrelated to gender.
（注意这里从过去时态过渡到现在时态）
材料与方法（Materials and Methods）：
对写论文之前自己所做工作的描述，通常采用一般过去时。
例如：（例1） Total phosphorous (TP) and total nitrogen (TN) were measured in the laboratory using standard procedures.
（例2）The standard protocol was followed for the preparation of the media from stock solutions.
结果（Results）：
对自己得出的研究结果，采用过去时进行详细的阐述。
例如：（例1）Overall, more than 70% of the insects collected were non-phytophagous.
（例2） Following activation of NT oocytes with strontium, the cell cycle resumed in both groups.
描述图表内容通常采用现在时。
例如：（例1） Figure 1 displays the comparative variation in the morphology of donor chromatin in both age groups of oocytes.
（例2） Table 1 below shows the stream flows calculated for each stream using Equation 1.
图1和表1表达的论文写作时的状态，所以要用现在时。
讨论（Discussion）：
采用现在时表达研究结果的意义。
例如：Removal of vegetation for agricultural purposes appears to negatively affect the water quality of streams.
采用过去时总结研究结果，并采用现在时对研究结果进行讨论与解释。
例如：（例1）Weight increased as the nutritional value of feed increased. These results suggestthat feedshigher in nutritional value contribute to greater weight gain in livestock.
（注意这里用过去时描述了实验发现，但在讨论这个发现的意义时用的是现在时。）
（例2）Leaf carbon and phenolic content did not differ across sites, indicating that the response of
secondary plant chemicals such as phenolics to water is complex.
（这句的描述几乎没有假设的意思，表示作者坚信其研究结果和结论的正确性及相关性）
结论（Conclusion）：
可用多种时态，使用过去时强调过去的研究成果，并可采用现在时或将来时表达未来的研究方向或研究前景。
例如：Although the study found evidence of tillage and irrigation within the study area, from the data collected it was not possible to determine if the effects of agriculture upstream cause (or caused) higher levels of total nitrogen downstream. Further studies are therefore necessary to determine the effects of agriculture on the health of Stringybark Creek.
