学术写作需要大量的解释和谨慎的用词。而要做到完全清晰就有可能导致句子过于冗长，尤其是在描述研究方法或结论时。不同语言在描述此类句子时会非常长，但就学术写作而言，英语通常更简洁。本文举例说明了如何将过于冗长的句子切成小段，使读者更容易理解。

遗憾的是，并没有一个很好的规则来规定何时应该拆分句子。BioEssays上的一篇社论简要调查了三大生物科学期刊，发现每篇论文的平均句子长度为25到30个单词。即使是词汇量丰富的多产作家查尔斯-狄更斯（Charles Dickens），每句话的平均长度也不到20个字。

当然，任何文章都需要一些超过20个字的句子。(每个句子20个字只是一个理想的平均值。如果任何句子大大超过了这个字数，你不妨重新审视一下，看看是否可以用一些更短的句子来表达同样的意思。

列出基本信息

有些长句子只是在传达作者希望读者了解的一些事实。但是，如果这些事实之间没有很强的联系，那么把它们都写成一个句子就没有什么好处了。下面是古生物学家肯尼斯-卡彭特（Kenneth Carpenter）的例子：

On the tops of crinoids is a circle of plates called radials, which in some primitive crinoids is further divided into a lower inferradial and an upper superradial, and below the radials is a circlet of plates called basals. （39个单词）由于这个句子只是简单地传递信息，因此可以将其分为三个句子，这不会有什么不好影响：Because this sentences simply relays information, it can be divided into three sentences without any adverse effect: On the tops of crinoids is a circle of plates called radials. In some primitive crinoids, these radials are divided into lower inferradials and upper superradials. Below the radials is a circlet of plates called basals. （平均每句 13 个字）。

以 although、because、despite 等开头的句子

虽然设立大纲对保持思维流畅和贴合主题很有帮助，但实际上，在想法尚不完全的时候动笔，写作速度更快，质量也更高。写作时一个创造性和交互性的过程，可以一边撰写，一边建立观点和想法。

其他句子包括两个具有特定关系的独立概念。常见的例子包括描述一个观察结果的原因、两个相反的观察结果或一个事件的发生，即使另一个事实似乎排除了它。

Because only certain proteins are transported into the nucleus of the cell, and many such proteins contain nuclear localization signals (NLSs) that are recognized by importins, we searched the primary sequences of the two novel proteins for homology to canonical NLSs. （40个字）这句话提供了一些信息，作为同源性搜索的依据。在第二句中加入 "therefore"一词，取代了原语句开头的 "because"的作用。因此，可以将背景与实验设计分开如下： Only certain proteins are transported into the nucleus of the cell, and many such proteins contain nuclear localization signals (NLSs) that are recognized by importins. We therefore searched the primary sequences of the two novel proteins for homology to canonical NLSs. （现为两句分别24 和 16 个字）Although several previous studies have shown that there are seven components of the classical Heptad complex, our data show that an eighth protein should be considered an integral part in certain cell types and developmental stages.(36 个单词）与 " because "一样，带 " although "的句子结构也可以重新编辑，以便将出乎意料的观察结果与先验信息或对比信息区分开来。括号中显示了两种可能性Several previous studies have shown that there are seven components of the classical Heptad complex. [In contrast,] our data [, however,] show that an eighth protein should be considered an integral part in certain cell types and developmental stages.(两个句子分别是 15 和 21-22 字）

时间轴或疾病进展

当作者描述多步骤过程，尤其是因果关系时，通常会出现长句。短句仍然是可取的。适当使用过渡词和/或明确的句子主题可以将过程统一为一个概念。

The progression of liver disease to later stages occurs when hepatic stellate cells are activated by reactive oxygen species and cytokines such as TNF and produce profibrotic mediators, which cause the expression of receptors for factors such as PDGF. （39 个字）

有关疾病进展起始阶段的信息可以从所描述的具体效应中摘出来：The progression of liver disease to later stages occurs when hepatic stellate cells are activated by reactive oxygen species and cytokines such as TNF. Activation leads to the production of profibrotic mediators, which cause the expression of receptors for factors such as PDGF. （两个句子分别是 24和 19字）

很多编辑可能会像波特-斯图尔特大法官（20世纪50年代任美国联邦最高法院大法官）描述猥亵罪一样描述冗长的句子："我一看就知道"。不过，我们还是希望这些例子能帮助你判断一个句子是否变得太长，以至于读者无法正确获取到信息。