The forms of the infinitive
I ought to call them. (to-infinitive)
I had better call them. (bare infinitive)
In the negative, not usually comes before the infinitive:
I ought not to call them.
I had better not call them.
In some cases, the verb in the main clause is negative, not the infinitive:
I want to call them.
I don't want to call them.
As the infinitive has no tense, it does not in itself indicate the time of the action that it refers to. However, it can have aspect, which shows the temporal relationship between the action expressed by the infinitive and the time of the preceding verb. There are four types of infinitive, each of which has an active and passive form:
|Simple infinitive||(to) write||(to) be written|
|Continuous infinitive||(to) be writing||(to) be being written|
|Perfect infinitive||(to) have written||(to) have been written|
|Perfect continuous infinitive||(to) have been writing||(to) have been being written|
The simple infinitive refers to the same time as that of the preceding verb:
I was glad to see her.
He must be very happy.
I'll arrange a meeting with the manager.
My son's football coach is said to be very strict.
The continuous infinitive refers to the same time as that of the preceding verb and expresses an action in progress or happening over a period of time:
I'm glad to be sitting here.
You must be joking.
This time next week, I'll be lying on the beach in Croatia.
Vincent was reported to be staying in Paris at that time.
The perfect infinitive refers to a time before that of the preceding verb:
I'm glad to have studied at that school.
They must have forgotten about the deadline.
By next week, they'll have finished painting the rooms.
Lucy was assumed to have left the day before.
Perfect continuous infinitive
The perfect continuous infinitive refers to a time before that of the preceding verb and expresses an action in progress or happening over a period of time:
I'm glad to have been living in Barcelona for the last ten years.
He must have been waiting for ages.
Soon, he'll have been running for four hours.
The organisers were thought to have been preparing for days.
Passive forms are also possible:
Your composition has to be typed. (passive simple infinitive)
The spy's phone was believed to be being tapped. (passive continuous infinitive, rarely used)
This sonnet must have been written by Shakespeare. (passive perfect infinitive)
The picture is believed to have been being painted for years. (passive perfect continuous infinitive, rarely used)