连词的分类
1、按连词的构成可将其分为以下几类：
1) 简单连词，如and, if, or, because, but, so
2)关联连词，如both … and …, not … but …, not only … but also …
3)分词连词，如supposing, providing, provided, given
4)短语连词，如as if / through, even if / through, as / so long as
2、连词的性质可将其分为以下几类：
1 并列连词，如and, but, or, nor, so, for, as well as, while, when, not only … but also …, both … and …, either … or …, neither … nor, therefore, yet, nevertheless, however等。它们用来连接平行的词、词组或分句。
2 从属连词，如after, when, before, as, while, since, until, till, although, though, if, even if, unless, lest, because, than, that, whether, so that, as soon as, as long as, in order that, as though, suppose (that), provided (that), in case (that), now (that), on condition (that), seeing that, so … that, such … that, as … as, so …as等。它们用来引导从句。