简单地说，英语复合句所涉及的三大从句为：名词性从句（包括主语从句、宾语从句、表语从句、同位语从句），形容词性从句（即定语从句），副词性从句（即状语从句）。1. 引导名词性从句通常有三类词：一类是连接词 that, whether, if；另一类是连接代词who, whom, whose, what, which 以及 whoever, whomever, whoseever, whatever,whichever；还有一类是连接副词how, when, where, why。2. 引导形容词性从句（即定语从句）通常有两类词：一类是关系代词that, which, who, whom, as, whose等；另一类是关系副词where, when, why。3. 引导副词性从句（即状语从句）的叫从属连词。不同作用的状语从句通常由不同的从属连词来引导。如：(1) 引导时间状语从句的从属连词主要有when, while, as, whenever, before, after, since, until, till, as soon as, the moment, the minute, the second, the instant, immediately, directly, instantly, once等。(2) 引导条件状语从句的从属连词主要有if, unless, as [so] long as, in case 等。(3) 引导目的状语从句的从属连词主要有 in order that, so that, in case, for fear等。(4) 引导结果状语从句的从属连词主要有so that, so…that, such…that等。(5) 引导原因状语从句的从属连词主要有because, as, since, seeing (that), now (that), considering (that) 等。(6) 引导让步状语从句的从属连词主要有although, though, even though, even if, while, however, whatever, whoever, whenever, wherever等。(7) 引导方式状语从句的从属连词主要有as, like, as if, as though, the way等。(8) 引导地点状语从句的从属连词主要有where, wherever, everywhere等。(9) 引导比较状语从句的从属连词主要有than和as…as。