副词可被用来修饰或限制动词、形容词，以及其他副词，因此副词在句中的位置会大大影响一句话的意思。让我们以副词only为例，看看副词位置的重要性：
- Only I drive red cars; no one else drives them.
- I only drive red cars; I do not park them.
- I drive only red cars; I do not drive green cars.
- I drive red-only cars; I do not drive multicolored cars.
- I drive red cars only; I do not drive red motorcycles.
因为only较常出现在英语语法书中，多数作者都能正确使用。然而，我在写作教学时，常常发现其他副词被错置的情形，其中最常见的是predominantly、mainly、mostly。让我们来看看下面这个例句：
Eukaryote-specific rRNA is predominantly located on the surface of the ribosome.
这里误用predominantly来修饰动词locate，而实际上它应该修饰on the surface of the ribosome这个副词词组才对，修改此句如下：
Eukaryote-specific rRNA is located predominantly on the surface of the ribosome.
根据我的观察，这类错误均是误将副词置于动词之前。以下例句均属于此类副词误置。
原句1：Under neutral conditions, the O-acyl isopeptides were predominantly converted to the corresponding monomeric amyloid β peptides.
改句：
Under neutral conditions, the O-acyl isopeptides were converted predominantly to the corresponding monomeric amyloid β peptides.
原句2：Cystathionine β-synthase catalyzes the formation of H2S, which predominantly exists as SH– at physiological pH.
改句：
Cystathionine β-synthase catalyzes the formation of H2S, which exists predominantly as SH– at physiological pH.
原句3：Most other anthropogenic emissions, such as emissions related to fossil fuel combustion, mainly occur in urban areas.
改句：
Most other anthropogenic emissions, such as emissions related to fossil fuel combustion, occur mainly in urban areas.
原句4：
Humans are mainly exposed to PAHs by three routes: digestion, inhalation and dermal contact.
改句：
- Humans are exposed to PAHs mainly by three routes: digestion, inhalation and dermal contact.
- Humans are exposed to PAHs by three main routes: digestion, inhalation and dermal contact.
原句5：The inhibitory activity of the plant extract was mostly due to coumarin.
改句：
The inhibitory activity of the plant extract was due mostly to coumarin.
原句6：
The evolution of H2O at 85–100 °C was mostly due to vaporization, whereas H2O evolution at 300–350 °C was mostly due to intramolecular H2O elimination.
改句：
The evolution of H2O at 85–100 °C was due mostly to vaporization, whereas H2O evolution at 300–350 °C was due mostly to intramolecular H2O elimination.
错误的副词位置常常误导读者与审稿人，從而产生理解上的偏差。所以，建议多花几分钟用文字处理器的搜寻功能，来确认您是否将这副词都放在正确的位置上。
参考来源：
Coghill, Anne M., and Lorrin R. Garson. The ACS Style Guide: Effective Communication of Scientific Information, 3rd ed. (Washington, DC: American Chemical Society, 2006), p. 45.
Cook, Claire Kehrwald, Line by Line: How to Improve Your Own Writing (Boston: Houghton Mifflin, 1985), pp. 22–29.
Einsohn, Amy, The Copyeditor’s Handbook (Berkeley: University of California Press, 2000), p. 360.
Garner, Bryan, Garner’s Modern American Usage, 3rd ed. (Oxford: Oxford University Press, 2009), p. 592.
Stevens, Matthew, Subtleties of Scientific Style (Thornleigh, Australia: ScienceScape Editing, 2007), p. 47.
