a.       if引导的条件状语从句

if是引导的条件状语从句最常见的连词，意为“如果”。

If you fail in the exam, you will let him down.

b.       unless引导的条件状语从句

unless引导的条件状语从句，意为“除非，如果不…”。

Unless it rains, the game will be played.

He will not phone me, unless something unexpected happens.

c.        as/so long as, on condition(that)引导的条件状语从句，意为“只要”。

You can go out, as long as/so long as/ on condition that you promise to be back before 11 o’clock.

d.  条件状语从句中一般要用现在时态来代替将来时态。

e.  条件状语从句经常可以用“祈使句+ and/ or...”来转换。

eg.: If you listen carefully, there won’t be any difficult points for you.

→ Listen carefully, and there won’t be any difficult points for you.

Ø         除了真实条件句之外，还有虚拟条件句，从句中的条件和结果都与事实相反。虚拟条件句的主要形式

见下表：

5）   地点状语从句

引导地点状语从句的常用词有where, wherever等, 地点状语从句可以置于句首，句中或句末。

Where he made mistakes, he admitted these willingly.

I’ll pick you up where you get off the bus.

Wherever he went he carried a notebook around with him, in which he wrote down his ideas.

Ø         地点状语从句和定语从句的区别

eg.: Go back where you came from.

Go back to the place where you came from.

6）   目的状语从句

引导目的状语从句的常用词有that, so that, in order that, for fear that, in case(that), lest等, 地点状语从句可以置于句首，句中或句末。

a.       in order that, so that引导目的状语从句

in order that常用语正式文体，可置于句首，也可置于句尾；而so that往往只置于句尾，但也有置于句首的，so that短语中有时可省略that.

He is keeping quiet that he may not disturb his father.

We climbed high so (that) we might get a better view.

The teacher raised his voice in order that the students in the back could hear more clearly.

b.       for fear that, in case(that), lest引导目的状语从句

for fear (that)表示目的时，意为“唯恐，以防”；in case意为“目的是，以防，以免，以防有某种情况发生”；lest意为“以防”

Take the umbrella with you lest/in case it should rain.

We had a meeting and talked the matter over face to face, for fear that there should be any misunderstanding.

Ø         that与so that可以引导结果状语从句和目的状语从句，要区别这两种从句，只要看从句中的动词，

因为在目的状语从句中，一般要用can, could, may, might等助动词，而结果状语从句中则不用。

7）   结果状语从句

引导结果状语从句的常用词有so that, so… that, such… that, so等, 地点状语从句一般置于句末。

a.       so that引导结果状语从句

We moved to the country so that we were away from the noisy and dull city.

She is ill so that she can’t get out of bed.

b.       so… that引导结果状语从句

形容词/副词

                   much/little+不可数名词        &n