一般判别二者之间的区别使用是根据不同的标志词来确定的，或者说用marker来确定它们。例如，动词不定式表示目的的有in order to, so as to。表示结果的有：so … as to, such … as to, enough to, too … to等。请看例句：

He shouted so as to be noticed.（目的）

She started early in order to avoid the rushing crowds.（目的）

Would you be so kind as to lend me your bike?（结果）

He is such a fool as to think that his idle chat can influence others.（结果）

The boy is old enough to look after himself.（结果）

His eyesight is too poor to read such small letter.（结果）

She wept to hear the news.（原因）

I rejoiced to hear that my son had been admitted into the famous university.（原因）

分词的表现形式是通过悬垂结构的句意来判断的，但是要请注意，悬垂结构中的逻辑主语一定是后面主句中的主语，检验的办法就是用主句的主语很分词结构还原成一个状语从句。如：

  ① 时间

Looking up suddenly, Robert saw a rainbow in the sky.

Floating on water, a ship displaces an amount of water equal to its own wweight.

Hearing the news that her son was rescued, she felt greatly relieved.

  ② 原因

Not knowing how to pronounce the word “plough”, the Frenchman looked up it in a dictionary.

Considering the importance of the experiment, they checked the result again and again.

Living in a remote village, we rarely have visitors coming.

  ③ 条件

This same thing, happening in the peacetime, would be a great disaster.

Unless meeting with unexpected difficulties at the office today, I shall be home early tonight.

  ④ 让步

Granting the achievements to be great, we have no reason to be conceited.

Walking and sleeping, he has the plan in his mind.

The chemical composition of water is H2O, whether being solid, liquid or vapor.

   ⑤ 结果

Their car was caught in the traffic jam, thus causing their delay.

We introduced a lot of advanced devices, thus saving much time and labor.

  ⑥ 目的

The people are working hard, striving to realize our country’s modernization.

We held a meeting, marking the anniversary of his death.

  ⑦ 方式（也称做伴随）

Theu stood by the roadside, watching the parade.

She stood motionlessly vacantly, looking at the sea.

They sat together, studying carefully the design of the new project.

5）省略不定式小品词to的情形

   在不定式中，小品词to有时可以省略。主要在以下几种情形中：

  ① 在由make, let, see, feel, watch, have, hear, help, notice, observe, listen to, look at等动词引出的作宾语补语的情况时。

  ② 在介词but, except, besides 后（动词谓语必须是do，否则还需要小品词to）。如；

What do you like to do besides swim and play football?

Before breakfast we have no class but (except) to read English aloud.

When the enemy surrounded the house, they had no choice but to burn all the important documents.

  ③ 在had better, had best, had as good（宁可）, would rather … than, would sooner … than, might as well, rather than后。如：

He had as good study English instead of German. 他宁可学英语也不愿意学德语。