动词不定式的使用方法

不定式结构作主语

1、不定式前置

1) Derive [A] mineral resources from [B] sedimentary rock [C] is a [D] major modern industrial activity.

2) in the matriculation for postgraduate in a short time is realy a hard nut.

[A] To make high scores[B] To make low goal[C] To the high scores[D] Make the low goals

2、上述形式通常情况不多见，作为考试的规范英语，假如不定式较长，看上去头重脚轻,则可由代词it作形式主语，而将不定式放到后面

It is really a hard nut to get high scores in the matriculation for postgraduate in a short time.

3) John admitted that its always difficult.

[A] for him being on time[B] being on time for him

[C] for him to be on time[D] on time for him

4) It is difficult for me [A] to be concentrating [B] while someone [C] is using [D] a vacuum cleaner.

3、不定式后置的状况不只限于动词是系动词，也适用于其他动词

It took us a great deal of efforts to finish that task.

It made him extremely happy to get contact with his family in Taiwan since they separated more than 40 years ago.

4、不定式结构所表示的动作是哪个做的，即不定式的逻辑主语，一般可以在特定的上下文中能看出，也可以通过带for +名词短语辨出

It is quite important for us to read good books during the period of general review。

It is not difficult for those who study maths well to pass the exam.

5、在某些形容词作表语时，不定式后可以加of来引导出其逻辑主语

It is very kind of you to help me./It is stupid of him to do such a silly thing.

间或也可用for + there to be 表示。

Its a great pity for there to be much trouble in the company.