SCI论文写作细节 | 分号与圆括号，这么用能给你的文章加分！
The following article is from Super立方体的科技英文写作教室 Author Super立方体
上一篇中介绍了英文标点中「 - / – / — 」三种横线的用法，这篇来说说分号和圆括号的事。对于这两种标点，咱中国的学生可能是因为不太熟悉，使用得相对较少。其实，分号和圆括号有一些很好用的功能，在科技论文中穿插在适当的地方，会有承顺文气、平滑逻辑、消除歧义等妙用。今天这一篇就结合实例来具体说一说。
分 号
分号 (semicolon) 可以认为是介于句号 (period) 和逗号 (comma) 之间的一种标点。它与句号的相同之处在于，两者都是用来分隔两个完整的句子——换句话说，分号前后的句子在语法上都应该是独立完整的，中间不需要连词，这一点与逗号不同。而它与句号的区别则在于，在文气和逻辑上，分号并不像句号那样有很强的分隔作用，这一点则于逗号接近。试对比下面三个句子：
Noble metals generally exhibit excellent catalytic performances, however, their applications are limited by the relatively low abundance and high cost. ✕
Noble metals generally exhibit excellent catalytic performances. However, their applications are limited by the relatively low abundance and high cost. ✓
Noble metals generally exhibit excellent catalytic performances; however, their applications are limited by the relatively low abundance and high cost. ✓✓
例句1中，两个句子以逗号分隔开，两句之间在逻辑上是转折关系，但中间缺少连词（注意，however是副词而不是连词），所以在语法上是错误的。
例句2中，两个句子以句号分隔开，所以在语法上并无不妥 (grammatically correct) 。但从两句之间的逻辑关系上来看，则显得有些断裂，即文气不畅。另外从英文中多长句这一习惯来看，两句之间用句号断开也显得有些碎片化。
例句3中，两个句子以分号分隔开，既不像逗号一样需要连词，也不像句号一样将文气截断——换句话说，既保证了语法上的正确性 (grammatical correctness) ，又保证两个句子在逻辑上的连贯性 (logical continuity) ；同时两句连缀成一个长句，也符合英文的表达习惯。
✪ 简而言之，从语法上来说，任何一个分号都可以替换成句号；但从文气上来讲，分号更突显前后两句在逻辑上的「藕断丝连」。下面按各种逻辑关系各举几例：
1. 并列关系（常与冒号配合使用）：
Matter can undergo two types of changes: chemical changes or reactions are changes in composition; physical changes are changes in state or physical form and do not affect composition.
The four basic stages of the scientific method are: (1) XXX; (2) XXX; (3) XXX; (4) XXX.
2. 转折关系：
All truths are easy to understand once they are discovered; the point is to discover them.
Gamma ray is not made up of particles; rather it is electromagnetic radiation of extremely high penetrating power.
3. 递进关系：
Astronomy's tools are not only diverse; they are also changing rapidly.
As designed, both space probes sent by NASA will not only detect Earth-like planets around nearby stars; they will also measure the planets’ physical and chemical characteristics.
4. 因果关系：
When a static positive charge builds up in one place, a negative charge of equal size appears somewhere else; therefore, charge is balanced.
The outer planets move slowly and their orbits are very large; thus they take a long time to go once around their orbit.
5. 对比关系：
Objects at rest stay at rest; objects in motion stay in motion.
An ordinary microscope uses a beam of light to illuminate the object; an electron microscope uses a beam of electrons.
6. 承接关系：
In the word photon, phot- means light; -on signifies a particle.
Formic acid is injected by an ant when it bites; this leads to the burning sensation that accompanies the bite.
7. 进一步释义：
Mass and volume are extensive properties; they depend on the amount of matter in a sample.
The properties of nonmetals are generally opposite those of metals; for example, nonmetals are poor conductors of heat and electricity.
✪ 另外，如果分号隔开的句子之间在结构上相似，在用词上重复，则可以将重复的部分适当省略，用逗号代替，这样可以减少啰嗦冗余之感。试比较：
By 1994, astronomers had found only three exoplanets; by 2017, they had found about 3500.
By 1994, astronomers had found only three exoplanets; by 2017, about 3500.
Some telescopes are on mountaintops; others are in Earth orbit; yet others are in interplanetary space.
Some telescopes are on mountaintops; others, in Earth orbit; yet others, in interplanetary space.
由此可见，分号间隔的句子中将重复的内容 (红色部分) 替换成逗号，可以让语句变得简洁紧凑。
圆 括 号
圆括号 (parentheses) 的作用是增加一些补充说明的信息，圆括号中的内容可能是一个单词（甚至一个前缀/后缀），一个短语，或一个或几个句子。
However, the conclusion was based on some (over)simplified assumptions. I would like to suggest the authors add some (semi)quantitative analysis results.
An oscillating (and therefore accelerating) electric charge causes a disturbance that moves outward through space as an electromagnetic wave.
Sirius, the brightest star in the sky, lies within the boundaries of the constellation Canis Major (meaning the “big dog”).
Nearly all short-period comets have prograde orbits; that is, they orbit the Sun in the same direction as the planets. (Comet Halley, with its retrograde orbit, is an exception.)
注意：圆括号中的内容必须在语法上是可有可无的。换句话说，如果把括号中的内容去掉，原句在语法上必须仍是正确的。试辨析：
The Sun (and its associated planets) are located about halfway out from the center of the Milky Way Galaxy. ✕ 【主谓不一致】
The Sun (and its associated planets) is located about halfway out from the center of the Milky Way Galaxy. ✓
The Sun and its associated planets are located about halfway out from the center of the Milky Way Galaxy. ✓
✪ 科技论文要求论述严谨，而圆括号可以起到「打补丁」的作用，减少语义上的漏洞，让表意更加精准且丰富。例如：
Salts of Group 1 cations (with some exceptions for Li+) are soluble.
For most materials (water ice being a rare exception), the solid form of the material is more compact than the liquid form.
With the speed of light, it will take us a bit over four years to cover the distance from Earth to the nearest star (other than the Sun).
The European Union has funded two specific flagship efforts, one in graphene (and other two-dimensional materials), and the Human Brain Project, which seeks to simulate the human brain.
当然，引入补充说明的成分还可以借助逗号 (comma)或长划线 (em dash)，但相比之下，圆括号的优点在于可以让语句显得更加紧凑、有层次而不至于琐碎或喧宾夺主，有时还可以起到消除歧义的作用。试看下面几例：
For more challenging reactions (such as toluene oxidation), no catalysts capable of high-efficiency and large-scale conversion have been reported.
【此处若用逗号，会显得有些碎片化】
Because the electric field points directly away from a positively charged particle (or directly toward a negatively charged particle), the force that a second charge feels is either directly toward or directly away from the first charged particle.
【此处的圆括号使前半句更加紧凑，且降低了前半句的份量感；如果橙色部分不放到圆括号里，前半句会显得有些啰嗦笨重，让整个句子有「头重脚轻」之感】
Human-made space probes have landed on Mars, Venus, Titan (Saturn’s largest moon), and an asteroid.
【此处橙色部分为注释说明成分，圆括号可使层次更加分明；若将圆括号改为逗号，则会产生歧义】
✪ 多说一句，在一些不太严肃的语境中，圆括号还很适合用来吐槽，提升幽默感。试体会：
Long before Columbus’s famous (or possibly infamous) journey to the New World, anyone who had read Aristotle or other Greek philosophers knew that Earth is a ball.
【括号里的内容说明，哥伦布发现新大陆之旅是举世闻名的，但在某种意义上也是臭名远扬的】
After three weeks on set, the cast was fed up with his direction (or, rather, lack of direction).
【括号里的内容说明，演员们都受够了导演低水平的导戏，甚至认为那都不能叫「导戏」】
怎么样？你能体会到括号里那种暗搓搓小声吐槽的感觉吗？
参考资料：
https://www.thepunctuationguide.com/semicolon.html
https://www.thepunctuationguide.com/parentheses.html
------【文中若有谬误，欢迎留言指正】------
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