科技论文中常用的两种时态是现在时和过去时。一般而言，在表述观察结果、已完成的行为及特定结论时应使用过去时。例如，描述实验结果时要使用过去时，因为实验已经结束，而你的结果尚未成为公认的“事实”。因此，那些主要涉及你自身工作的内容，如“摘要”、“材料和方法”以及“结论”部分都应使用过去时。

C 例1

a  Higher temperatures resulted in less bud formation.

b  The three images were taken about 90 minutes apart.

        对于那些普遍认可的概念和观点用现在时表述。已经发表的结果通常被视为“事实”。 “前言”部分要使用现在时，因为其所介绍的是前人构建的知识。

C 例2

a  The newly discovered planet is at least as big as Pluto.

b  Most regions where this problem arises belong to category X.

        如果用过去时描述已经发表的工作的结果，则表示你不认为该结果是“事实”，而仅仅是观察结果。

C 例3

Sultan observed that certain species of bacteria respond to light stimuli.

        该句描述的是一个已经完成的实验。因此“observed”使用了过去时，然而“respond”却使用了现在时，这是因为这部分句子表述的是事实，是发表过的、已经存在的知识。

        “讨论”部分是探讨你的工作与前人工作的关系，这部分最难写，因为同时涉及现在时和过去时。记住，通常情况下，展现数据图表时用现在时，描述假说和原理时也用现在时。

C 例 4

The effect of TXY addition is shown in Figure 5.

      当观察被重复进行或从过去持续到现在，则使用现在完成时。

C 例5

X has been of interest for the past three decades.

        只有一种情况使用将来时，就是你的实验计划于将来实施。未来的实验一般不会出现在研究论文中，但会出现在基金申请中。

C 例6

We will examine if parallel universes exit.

练习：下列各句应使用过去时还是现在时（如果答案不只一个，请解释原因）。

1.       In our study, tree size __________(increase) with reduction of pesticides.

2.       The larva of the monarch butterfly__________(feed) on milkweed.

3.       In our study, we__________(find) that there are significant flattenings of the PES along the reaction Pth with increasing cluster size, as Fig. 5__________(indicate).

4.       In a study by Fermi, the vibrational levels__________(diverge) into the so-called Fermi dyad.

5.       Females of this species__________(have)a unique projection from he dorsal part of the thorax.

6.       Recent work by deValt (2001)__________(show) that nematodes__________(reproduce) readily in the laboratory.

7.       A phagemid construct encoding 2 transgenes in tandem__________(can) be used to transform E. coli cells.

8.       Table 3__________(show) that in our study, polychaetes__________(be) most abundant at depths of 10 to 16 m.

9.       Baumann (1997)__________(find) that this bacterium__________(is) highly sensitive to pH.

10.   We__________(observe) chemoattraction within 30 min of Shh addition.

11.   Identification of restriction factors__________(give) us more knowledge of the host cell restriction system.

12.   Our results__________(suggest) that the Asn5 glycosylation site __________(play) a critical role in the function of the KCEN 1 protein.

13.   We__________(investigate) high-quality single crystals of vanadium oxide.

14.   We__________(do) not observe rods in the diffraction patterns but instead well-defined Bragg spots, suggesting that at least 10 interatomic layers in the surface-normal direction__________(be)contributing to the interferences.

15.   Coupled climate-carbon cycle models__________(suggest) that Amazon forests__________(be) vulnerable to droughts, but satellite observations__________(show) a green-up in intact evergreen forests of the Amazon in response to a short, intense drought in 2005.

16.   The Ka value for β-cellobiosyl (approaching 10³ M^-1)______(be)comparable to that for many carbohydrate/protein interactions.

17.   Hundreds of species of reef-building corals__________(spawn) synchronously over a few nights each year, and moonlight_________(regulate) this spawning event.

18.   Arctic wind anomalies______(be) part of a global-scale pattern of highly unusual circulation in 2007, the causes of which______(be) as yet unclear.

19.   To map pathways of motion, all observed Bragg diffractions of different planes and zone axes__________(be examine) on the femtosecond to nanosecond time scale.

20.   ABSTRACT: The average translational energy_____(be) significantly lower than expected for the calculated surface temperature.

21.   SUMMARY: In conclusion, we_____(find) significant deviations from the equilibrium behavior in fs-laser induced desorption of CO/Ru.

参考答案

1. increased

2. feed

3. found … indicates

4. diverged

5. have

6. showed… reproduce

7. can

8. shows … were

9. found … is/was

10. observed

11. gives

12. suggest … plays

13. investigated

14. did… are

15. suggest…are… showed

16. is

17. spawn …regulates

18. were… are

19. were examined

20. was

21. found

摘编自《科技写作与交流》(任胜利 等 译. 科学出版社, 2012年出版)