C ． because，since，as  的区别

1． because 语气最强，表达的是未知的新信息，一般置于主句之后，也可以放在主句之前，用逗号隔开。在回答 why 引导的特殊疑问句时，或在强调结构 it  is/was that 和关联词 not but 引导的原因状语从句中，要用 because 。另外， because 还常和副词 just，merely 等连用。

2． since 往往表示的是已知的客观事实，或分析后的推理，引导的从句大多置于句首，主从句的时态一般相同。

3． as  表示的理由最弱，只是对主句的附带说明，重点在主句。 as  从句通常放在主句前。

Just because he doesn't complain，you must not suppose that he is  satisfied .你不可只因他不抱怨就以为他满足了。

You shouldn't get angry only because some people speak ill of  you .你不该仅仅因为有些人说了你的坏话就生气。

Since you're not interested，I won't tell you about it  .既然你不感兴趣，那我就不告诉你了。

as  you are unable to  answer perhaps we should ask someone else .因为你不能回答，也许我们该问一问别的人。

注意：

because 等词不能与 so 连用。

【误】 Because he was careless，so he failed in  the exam .【正】 Because he was careless，he failed in  the exam .由于他粗心，所以他考试不及格。

【正】 He was careless，so he failed in  the exam .由于他粗心，所以他考试不及格。

E ． now that

now that 既然，因为。 that 可以省略。

Now ( that ) dinner is  ready，go and wash your hands .既然饭已好了，洗手去吧。

Now you mention it  again，I do  remember .既然你又提起此事，我倒回想起来了。

F ． considering that，seeing that

这两个词和 since，now that 意思相近，都有鉴于事实，考虑到的意思。

Seeing that quite a  few people were absent，we decided to  put the meeting off .由于好些人都没到会，我们决定延期开会。 ( seeing 后面的 that 可以省略 )

Considering that they are just beginners，they are doing quite good job .考虑到他们才刚刚学做，他们干得算很不错的了。

G ． not that but that

这一结构相当于汉语的不是因为而是因为。

Not that I don't like the film，but that I have no time for it  .不是因我不喜欢看这部电影，而是因为我没有时间看。

四、目的状语从句

目的状语从句是表示行为目的的从句。引导目的状语从句的主要连词有 that，so ， so that，such that，in  order that 等，从句中常常使用一些情态动词，如 can，could，may，might，should 等。

 a  ． that，so that ， in  order that 表示为了，以便，一般放在主句之后。 that 语气较弱，用的较少，多用 so that 。

Let's take the front seats that we may see more clearly .我们坐前排吧，这样我们可以看得更清楚些。

Man does not live that he may eat，but eats that he may live .人生存不是为了吃饭，而吃饭是为了生存。

They hurried so that they might not miss the train .他们为了不误火车，才急急忙忙的。

in  order that everyone present might hear her clearly，she raised her voice again .为了使在场的每个人都能听清楚，她再次提高了声音。

注意：当主从句的主语一致时， so that 和 in  order that 引导的目的状语从句可以转换成相对应的动词不定式结构。

We got up early so that we would arrive in  time .为了能及时赶到，我们起得很早。

They hurried so that they might not miss the train .→ They hurried so as  not to  miss the train .他们为了不误火车，才急急忙忙的。

Betty saved money in  order that she could buy a  portable computer .→ Betty saved money in  order to  buy a  portable computer .贝蒂存钱是为了买一台手提电脑。

B ． in  case，lest，for fear that 几个短语都表示万一，惟恐，含有否定的意义。

Better take more clothes in  case the weather is  cold .最好多带些衣服以防天气会冷。

Take an  umbrella in  case it  rains .以防下雨，带把伞。

五、结果状语从句

结果状语从句是表示事态结果的从句。引导结果状语从句的连词有： that，so ( that )，so that，such that 等。结果状语从句通常置于主句之后。

a  ． so，that，so that

这三个词都可以引导结果状语从句。 so that 最为常用， so 或 that 常用于口语或非正式文体中。

What has happened that you look so worried?

发生了什幺事，使你显得如此担心？

I didn't plan the work well，so that/so I didn't finish it  in  time .我没把工作计划好，结果没按时完成。（ so that 从句常用逗号与主句隔开）

The room was packed with people，so that we couldn't get in  .房间里挤满了人，我们进不去。

C ． so ... that so ... that 如此以致。其引导的果状语从句有如下四种结构：

1． so +形容词副词+ that -从句

The village is  so small that it  cannot be  shown in  the map .这村子太小，所以这地图上没有。

The wind was so strong that we could hardly move forward .风刮得那么大，我们简直寸步难行。

2． so +形容词+ a an +单数名词+ that -从句

 it  was so hot a  day that they all went swimming .天是那么的热以致他们都去游泳了。

He made so inspiring a  speech that everybody got excited .他发表了如此鼓舞人的演讲以致大家都很激动。

3． so + many/few +复数名词+ that -从句

 I have had so many falls that I am black and blue all over .我摔了许多跤，以至于浑身青一块，紫一块。

He has so few friend that he often feels lonely .他朋友很少，所以经常感到孤独。

4． so + much/little +不可数名词+ that -从句

I had so little money then that I couldn't even afford a  used car .我当时囊中羞涩，甚至连一辆二手车都买不起。

He drank so much wine last night that he felt terrible .昨晚他喝了那么多的酒，他觉得很不舒服。

5.在 so +形容词副词+ that -从句结构中，如将 so +形容词副词位于句首，主谓语要倒装。

So excited was he that he could not say a  word .他很激动，一句话都说不出来。

So loudly did he speak that even the people in  the next room could hear him .他说得很响，连隔壁的人都能听见。