Cambridge Grammar of English Hardback with cd-rom a comprehensive Guide

Perfect infinitive clauses 

359e

A perfect infinitive clause can be used for events which did take place:

I am sorry for the Formans. 

To have worked so hard and then to have that done

to them overnight!

(they did work hard)

It may also refer to events that have not taken place:

[Millie is a cat]

But this time the button was too close to the wall. 

To have activated it, Millie

would have needed to use her paw like a finger.

(in this case, the following clause (would have needed) indicates that the event

was hypothetical; compare: To activate it, Millie would need to use her paw …

etc., where the possibility of activating the button is still open)

624 | Past time

Cambridge Grammar of English

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