一、状语从句分类及常用连词：
| 类别 |
连 词 |
| 时间状语从句 |
when, whenever, while, as, before,
after, since, till, once, as soon as,etc. |
| 地点状语从句 |
where,wherever |
| 原因状语从句 |
because, since, as, for, now that,
etc. |
| 目的状语从句 |
in order that, so that, that, etc. |
| 结果状语从句 |
so…that, so that, such…that,
that, etc. |
| 条件状语从句 |
if, unless, as(so)long as, etc. |
| 让步状语从句 |
though, although, even if, even
though, however, whatever, as,etc. |
| 比较状语从句 |
as…as, so…as, than, etc. |
| 方式状语从句 |
as, as if, as though, etc. |
二、相似连词的用法区别
1.when, while, as,
when表时间，从句需用延续性动词，切不可用瞬间动词。
while表时间，从句既可以用延续性动词，又可以用瞬间动词。
as表时间，与when相似，但侧重强调主从句动作同点或同段进行。
when, while后可以接分词短语。
2.because, as, since, for
| |
语气 |
位置 |
意义 |
| because |
最强 |
前或后 |
“原因”；表客观因果关系；回答“” |
| as |
较强 |
前 |
“由于”；把众人所知的事实当作理由 |
| since |
较弱 |
前 |
“既然”；就对方陈述的事实作为理由 |
| for |
最弱 |
后 |
“理由”；对某一事实进行推断的理由 |
注：上面所说的“前”，指从句在主句之前；“后”，指从句在主句之后。
3.so that, so…that, such…that
so that “以便”、“结果”表目的和结果。注意：在从句中有情态动词表目的。无情态动词表结果。
so…that “如此的…以致于”表结果。该结构常见于：
1.so+形／副＋that 2.so+形＋a(an)＋单数名词＋that 3.so＋many/much＋复数名词（不可数名词）+that
such…that “如此的…以致于”表结果。该结构常见于：
1.such＋a(an)＋形＋名词＋that 2.such＋形＋复数名词／不可数名词＋that
4.though, although, as,
though, although在句手表“尽管”两者都可以用。但句后不能再用but。
下列情况只能用though：
▲ as though (=as if); even if (=even though)
▲ 在句末表示“然而”
as表示“尽管”，从句的表语、状语等成分要倒装。
5.whatever, however,wherever, whenever
它们是what, how, where, when的强势语气。分别等于：
no matter what, no matter how
no matter where, no matter when
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