The Elements of Style 的13-19页上，有许多关于“逗号”的例子。我们在这里编译几个跟科技英语有关的例子。(Yes, I am cherry-picking.)
如果你的目标是写小说，应该看原版（免费下载）：
http://www.jlakes.org/ch/web/The-elements-of-style.pdf
I. ELEMENTARY RULES OF USAGE
4. Place a comma before a conjunction introducing an independent clause.
下面的两个例子都是“一句话，由两个部分组成”。第二部分由as (in the sense of "because"), for, or, nor, or while (in the sense of "and at the same time")引导，在其前面，需要用逗号。
The early records of the city have disappeared, and the story of its first years can no longer be reconstructed.
The situation is perilous, but there is still one chance of escape.
Two-part sentences of which the second member is introduced by as (in the sense of "because"), for, or, nor, or while (in the sense of "and at the same time") likewise require a comma before the conjunction.
如果句子中用“but”，它的前面常常会用逗号。如果一句话的两个部分是用“and”来连接（说明它们关系比较密切），则可以不加逗号。不信？请看下面的例子。
When the subject is the same for both clauses and is expressed only once, a comma is useful if the connective is but. When the connective is and, the comma should be omitted if the relation between the two statements is close or immediate.
I have heard the arguments, but am still unconvinced.
He has had several years" experience and is thoroughly competent.
5. Do not join independent clauses with a comma.
下面的例子不要用逗号，因为“两部分”是独立的。为了说明它们之间有关联，可以用分号（；）。
If two or more clauses grammatically complete and not joined by a conjunction are to form a single compound sentence, the proper mark of punctuation is a semicolon.
Mary Shelley"s works are entertaining; they are full of engaging ideas.
It is nearly half past five; we cannot reach town before dark.
自然，这种情况也可以不用分号，用句号。请跟我来：
It is, of course, equally correct to write each of these as two sentences, replacing the semicolons with periods.
Mary Shelley"s works are entertaining. They are full of engaging ideas.
It is nearly half past five. We cannot reach town before dark.
如果你不喜欢分号和句号，可以这样玩：
If a conjunction is inserted, the proper mark is a comma. (Rule 4.)
Mary Shelley"s works are entertaining, for they are full of engaging ideas.
It is nearly half past five, and we cannot reach town before dark.
有兴趣的童鞋，可以品味一下上面的三种写法。
A comparison of the three forms given above will show clearly the advantage of the first. It is, at least in the examples given, better than the second form because it suggests the close relationship between the two statements in a way that the second does not attempt, and better than the third because it is briefer and therefore more forcible. Indeed, this simple method of indicating relationship between statements is one of the most useful devices of composition. The relationship, as above, is commonly one of cause and consequence.
下面的分号，是因为其后面的副词（adverb），即accordingly, besides, then, therefore, or thus。
Note that if the second clause is preceded by an adverb, such as accordingly, besides, then, therefore, or thus, and not by a conjunction, the semicolon is still required.
I had never been in the place before; besides, it was dark as a tomb.
6. Do not break sentences in two.
In other words, do not use periods for commas.
I met them on a Cunard liner many years ago. Coming home from Liverpool to New York.
She was an interesting talker. A woman who had traveled all over the world and lived in half a dozen countries.
In both these examples, the first period should be replaced by a comma and the following word begun with a small letter.
Rules 3, 4, 5, and 6 cover the most important principles that govern punctuation. They should be so thoroughly mastered that their application becomes second nature.
原作者强调：规则3-6非常重要。希望大家反反复复地体会。
［科技英语写作基础（系列）：大纲（1）
http://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1146690
科技英语写作基础（系列）：大纲（2）
http://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1146716］
1. 语态
2. 常用时态
3. 一些标点符号（句号、逗号，参考The Elements of Style I 1-7)
4. 常用句型（主语谓语的“一致性”，参考The Elements of Style）
5. 段落（参考The Elements of Style）
6. 修改、修改、再修改（简洁为上／逻辑性／一致性）
请大家多提意见。
