状语从句 （adverbial clause） 是指句子用作状语时，起副词作用的句子。状语从句可以修饰谓语、非谓语动词、定语、状语或整个句子。
状语从句根据其作用可分为时间、地点、原因、条件、目的、结果、让步、方式和比较等从句。
状语从句一般由连词（从属连词）引导，也可以由词组引导。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。常见的状语从句及相应的从句连接词如下：
- 时间状语从句：while；when；before；whenever；as；after；till；until；since；once；ever since；as/so long as；as soon as；no sooner...than；hardly...when；scarcely/barely...when；the moment/minute/instant；on (the point of) doing...
- 方式状语从句：as；as if；as though；how；what；save that...
- 比较状语从句：as；than；as...as；not so...as；hardly...than...
- 让步状语从句：though；although；even if；even though；whether；as；however；no matter (what,how,when)；for all that；in spite of the fact that；granted that；regardless of the fact that...
- 目的状语从句：that；so that；in order that；lest；for the fear that；in case...
一、状语从句的考查重点包括：
① 根据上下文辨别状语从句的类型并选取相应的连接词。例如：
______their policy can be changed, the future for that country will be indeed bleak.
A. Even if
B. Unless
C. Now that
D. As long as
该句句意为“如果他们的政策不变的话，那个国家的前途就真的没有希望了”，故选 B 。
② 条件状语从句：主要考点为虚拟条件句，详见：专业四级语法 | 虚拟条件句考点归纳
③ 让步状语从句：词尾为 -ever 的“wh-疑问词”可以和 no matter+“wh-疑问词”换用，但是前者还可以引导名词性从句而后者不可以。例如：
- Whoever calls, tell him I'm out.
- No matter who calls, tell him I'm out.
二、各类表示比较的结构。主要包括：
① “as...as...”结构：
- The group has adventured as far as the Austrian alps. （远到……）
- As far as I know, he is kind. （就……来说，尽……）
- The hydroelectric station is as good as completed. （与……几乎一样，实际上等于）
- People are not perfect, so (as) long as they are genuine and sincere, trust them and be good to them. （只要……）
- He doesn't earn as much as I do. （和……同样的程度）
② “more/less...than...”结构：与其说……，不如说……
- They said that the decision was made more in sorrow than in anger.
他们说作出这个决定，与其说是出于气愤，不如说是出于悲伤。 - They said that the decision was made more in anger than in sorrow.
他们说作出这个决定，与其说是出于悲伤，不如说是出于气愤。 - The film is more of an ironic fantasy than a horror story.
这部影片与其说是恐怖片，不如说是带有讽刺意味的奇幻片。
③ “no less A than B”结构：A 和 B 一样……
- 她的能力并不比别人弱。
She's no less capable than the others.
④ “no more...than B”或“not...any more than B”结构：同 B 一样不……
- We can no more leave the party than fish can leave water.
我们不能离开党，正如鱼儿离不开水一样。 - This film is no more moving than that one.
这部电影不动人，那部也没意思。 - That is not good for me any more than it is good for boys and girls.
这不仅对我不好，对孩子们也不好。
⑤ “more than”结构：
- History is much more than the study of dusty old objects and events long past．（超出……的）
历史不仅仅是研究尘土飞扬的老物件和过去的大事件。 - I was more than happy to lend my support to such a good cause. （非常，极其）
我非常乐意给这样美好的事业提供援助。 - She was more than a little shaken by the experience. （不只是，不仅是）
这次经历对她产生了极大的震动。
⑥ “not so much as”结构：
- not so much A as B
与其说……是 A ，不如说……是 B - There came an explosion, not so much a bang as a shaking like an earthquake.
发生了一次爆炸，没听到一声轰然巨响，倒像是地震那样地面猛晃了晃。
⑦ “not so much as+v.”结构：甚至不；连……都不……
- I have not so much as heard of him, much less know him.
我都没怎么听说过他，更别提认识他了。
