Cool Breeze has written the following:
A. The present perfect in the passive:
A new house
has been built.
Two new houses
have been built.
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B. The perfect infinitive in the passive:
The perfect infinitive
is usually used with a defective auxiliary (also known as a modal
auxiliary). The defective auxiliaries are
can,
could; will, would; shall, should; may, might; must and
ought. With all of these, it is theoretically possible to have the passive auxuliary (to be) in the perfect infinitive (to
have been). The to-particle is used only with
ought.
Examples:
A new house may
have been built.
A new house should
have been built.
A new house must
have been built.
A new house will
have been built by the end of the year.
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The following is my question.
The sentence ' A new house will have been built by the end of the year' is a future perfct sentence. What has it to do with the perfect infinitive?
I will have learnt a lot about the perfect infinitive by the end of this month. This is a correct future perfect sentence like the sentence in question.