"to complete" vs "to have completed"

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hello,

The builders undertook to … the whole job by the end of the week.

a) to complete
b) to have completed

I do agree that answer “a” is correct; all the same, what about answer “b”.

Would it be a mistake if I chose it?

p.s. no context provided, sorry :frowning:

2

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I don’t think B works-- at the time they undertook the job, the completion was clearly in the future.
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3

What about the following:

…The builders undertook that they would have completed…

Would it be correct?

Thanks!

4

I think it right.

5

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Even worse, in my estimation! Undertook that they would complete is OK.
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6

I find that sentence to be awkward at best.

Here is a little feedback from the British National Corpus about just how uncommon the phrase “undertook that they would” is:
If you click here, you’ll notice that there are no hits at all in the BNC

For anyone who might be interested, there has been additional discussion on this topic in another forum.