使用并列连词
使用并列连词来表明它们所连接的元素在重要性和结构上是同等的。
并列连词的定义
并列连词连接语法上相似的元素（两个名词、两个动词、两个修饰语、两个独立从句）：
and
or
nor
so
but
for
yet
如何给并列连词加标点
当并列连词连接两个独立分句时，在并列连词前使用逗号（除非两个独立分句很短）。
不含非必要元素的连接词后面绝不能跟逗号。
Perhaps no budget is without some fat, but university officials argue that their unique function requires special standards of evaluation.
当复合句中的独立分句包含逗号来分隔引导性或非必要元素时，读者可能会对并列连词前的逗号感到困惑。在这种情况下，可以用分号代替逗号。
The figures at elite universities, particularly, are enough to cause sticker shock; yet the current increases at many schools are the lowest in a decade.
何时不宜使用并列连词
如果句子以并列连词开头，则后面不加逗号
Yet the typical tenured professor’s salary of $43,500 still represents 10% less buying power than the equivalent salary in 1970.
两个动词、两个主语、两个补语或由并列连词连接的两个宾语之间不使用逗号。
That confuses most analogies between universities and profit-making enterprises. [compound object of preposition]
Endowments and gifts make up the rest. [compound subject]
Georgetown, for example, has eliminated one-third of its graduate programs in the past five years and recently decided to close its dental school. [compound verb]
