如何判斷that引導什么從句

that可以引導名詞性從句、定語從句。that引導名詞性從句時（即主語、賓語、表語、同位語從句），在從句中無具體含義，只起連接作用，而且在從句中也不作任何句子成分。

that可以引導以下從句

1、用作關系代詞，引導定語從句 The only thing that I can do is to have a rest . 我唯一能做的事就是休息。

2、用作關聯詞，引導名詞性從句

That the earth turns around the sun is known to all. 地球圍著太陽轉這一點是眾所周知的。（引導主語從句）

It so happens that I know the man. 碰巧我認識那人。（主語從句）

I will see to it that everything is ready. 我會注意把一切準備妥當的。(賓語從句)

The trouble is that we are short of money.困難就在于我們缺錢。（表語從句）

There is no doubt that he is the best choice for this position. 無疑，他是這一職位的最佳人選。（同位語從句）

3、構成短語，引導狀語從句

Bring it nearer so that I may see it better .拿近一點，好讓我看清楚些。 ( so that 引導目的狀語從句)

She got up early , so that she caught the early bus. 她起得早，所以趕上了早班車。( so that 引導結果狀語從句)

In order that everybody should hear him , he spoke loudly. 他大聲說話，為了使大家都能聽得見。（in order that引導目的狀語從句）

Now that they have taken matters into their hands the pace of events has quickened.他們既然已著手自己來處理問題，事態的進展也就加快了。（now that 引導原因狀語從句）