实际上就是“不定式短语”,也叫infinitive phrase .
infinitive clause
a clause containing an infinitive as its main or only verb form,as to speak clearly in Try to speak clearly.
Also called infinitive phrase .
Infinitive clause as subect or object
Infinitive clause as subject
An infinitive clause can be the subject of a sentence.This was common in older English.
To err is human; to forgive divine.
To find fault with others is easy.
To make mistakes is easy.
In modern English infinitive clauses are rarely used as subjects.We more often use it as a ‘preparatory’ subject and put the infinitive clause later.
It is easy to find faults with others.
It is easy to make mistakes.