引导名词性从句的连接词

引导名词性从句的连接词可分为三类：

连词：

that（无任何词意）

whether, if（均表示“是否”表明从句内容的不确定性）

as if ,as though（均表示“好像”，“似乎”）

以上在从句中均不充当任何成分

连接代词：

What, whatever, who, whoever, whom, whose, whichever, whomever 连接副词：

When, where, how, why, how many, how much, how often

一、名词性that-从句

主语：That she is still alive is her luck. 他还活着全靠运气。

宾语：John said that he was leaving for London on Wednesday. 约翰说他星期三要到伦敦去。

表语：The fact is that he has not been seen recently. 事实是近来谁也没有见过他。

同位语：The fact that he has not been seen recently disturbs everyone in his office. 近来谁也没有见过他，这一事实令办公室所有的人不安。

形容词宾语：I am glad that you are satisfied with your job.你对工作满意我感到很高兴。

一、无词义

that引导名词性从句时无词义，仅仅起连接或引导从句的作用。例如：

I wish that she would understand me.我希望她能理解我。

It is said that there have been great changes in our hometown.据说，我们的家乡已经发生了巨大的变化。

The reason he didn't come was that he was ill. 他没有来的原因是他病了。There is a possibility that he is a spy.他可能是个间谍。

二、不作语法成分

that在引导名词性从句时，在从句中不能充当任何语法成分，对从句的结构无任何影响。It happened that it was raining heavily that day. 碰巧那天下大雨。

The fact is that we haven't enough money for that project.事实是我们没有足够的资金去实施那个项目。

They made a decision that they should take action to protect the nature. 他们做出决定：应该采取行动来保护大自然。

但要注意：在定语从句中，that作为关系代词，既用以代替先行词又在定语从句中作成分，这是区别定语从句与同位语从句的一个重要依据。

The news that we are invited to the conference is very encouraging.我们被邀请去参加会议的消息令人鼓舞。(that在从句中不作成分，该从句为同位语从句)。

The news that he heard isn't true.他听到的消息不真实。（that指代news，且作heard的宾语，故that引导的是定语从句。）

三、可省略或不可省略的情况

that用于引导名词性从句时，要注意其可省略或不可省略的情况。

1. 在主语从句中

当我们用从句作主语时，经常用it作形式主语，而将真正主语从句置于句末，在这种情况下，that一般不可省略。例如：

It is certain that he will succeed.他会成功是确定的。

2. 在宾语从句中

⑴若主句的谓语动词是appear，agree，learn，suggest，observe等时，that通常不可省略。例如：

We agreed that all the students must plant trees in the park. 我们一致赞同，所有学生须在公园里植树。

⑵若主句的谓语动词是hear，know，say，consider，understand，propose，be told等时，that可省略也可不省略。例如：

I heard (that) she had joined the army already. 我听说她已参军了。

⑶当主句的谓语动词是think，suppose，believe，dare，say等心理活动意义的动词时，宾语从句的引导词that通常要省略。例如：

I supposed they had finished all the work. 我猜想他们已完成了所有工作。

⑷在少数介词之后可带that引导的宾语从句，这时，"介词+that"已成为习惯搭配，且具有独特的含义，为此，不可省略that。如：in that"在于；因为"，but that"要不是......"，except that"除了......"等。例如：

The higher income tax is harmful in that it may discourage people from trying to earn more. 所得税过高是有害的，因为它可能使人不愿意多赚钱。

⑸某些"系动词+形容词"的系表结构之后，可带that引导的宾语从句，此时，that可省略也可不省略。例如：

I am delighted (that) you have got high grades in school.你在学校里成绩优秀，我很高兴。

⑹在"动词+it+宾语+that从句"结构中，我们用it作形式宾语而将that引导的真正宾语从句置于宾语补足语之后，这种结构中的that不可省略。例如：

I heard it said that he had gone abroad. 我听说他到国外去了。

3. 在表语从句中

表语从句置于系动词之后，充当表语，结构为"主语+系动词+表语从句"。引导表语从句的that可省略也可不省略。例如：

It seems ( that) it is going to rain. 好像要下雨了。

注意：在the reason is that 从句结构中，that 不可省略。例如：

The reason why he was dismissed is that he was careless.他被开除的原因是他工作马虎。