2、让步状语从句
(1)although与though可以引导让步状语从句,不能与but连用,但可以与yet连用.
Although they are poor,(yet)they are warm-hearted.
(2)even if或even though引导让步状语从句,表示"即使","纵然",用来使人注意下文所强调内容的性质.
I'll get there even if(though)I have to sell my house to get enough money to go by air.
(3)no matter后接上who、what、where、how等疑问词,也可以在这类疑问词后面加上ever构成whoever、whatever、wherever、however等.
Don't trust him, no matter what / whatever he says.
Whoever breaks the law will be published.
No matter how hard the work is, you'd better try to do it well.
(4)as也可以引导让步状语从句.要用倒装.
Child as(though)he is, he knows a lot.
Much as I like it, I won't buy.
Try as he would, he couldn't lift the heavy box.
3、原因状语从句:because, for, as, since, now that
(1)表示不知道的原因时用because,即说话人认为听话人不知道,因此because从句是全句最重要的部分,通常它被置于主句之后.
You want to know why I'm leaving? I'm leaving because I'm full.
for虽然表示不知道的原因,但其语气较because要弱得多,是可说可不说的话,它只能置于主句之后,这时,for是并列连词.如果不是因果关系,而是对前面主句的内容加以解释或推断时,只能用for.如:It's morning now, for the birds are singing.(很显然,鸟叫不可能是"现在已是早上"的原因.)
(2)表示已经知道的原因时用as或since,即某种原因在说话人看来已经很明显,或已为听话人所熟悉,因此它是句中不很重要的部分.since要比as正式一些,它们通常被置于语句之前,但有时却相反.
Seeing all of the children already seated, he said,"Since everyone is here, let's start."
(3)下列情况下只能使用because:
①在回答why的问句时;
②在用于强调句型时;
③被not所否定时.
4、地点状语从句:where, wherever
Make a mark wherever you have any questions.
We will go where the Party directs us.
5、目的状语从句:that, so that, in order that
注意:目的状语从句的谓语动词常与情态动词连用,否则可能是结果状语从句.不可置于句首.
6、结果状语从句:that, so that, so … that, such … that …
注意:so + 形容词/副词 + that从句;such + 名词 + that从句.
7、方式状语从句:as, as if(though)
I'll do as I am told to.
It looks as if it is going to rain.
8、比较状语从句:than, as
9、条件状语从句:if, unless, so (as) long as, in case, once, a far as, on condition that.
注意if与unless的区别:不能用and连接两个unless从句,即不能有… unless …,and unless … .
但if … not and if … not却不受此限.
You won't lose your weight unless you eat less and unless you exercise more.(×)
但可以说 … unless you eat less and exercise more.
10、注意状语从句中从句的省略现象
(1)连接词 + 过去分词
Don't speak until spoken to.
Pressure can be incrased when needed.
Unless repaired, the washing machine is no use.
(2)连词 + 现在分词
Look out while crossing the street.
(3)连词 + 形容词/其他
常见的有it necessary、if possible、when necessary、if any等
责任编辑：sealion1986
