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There ___ enough space to mention all the scholars on whose work I have drawn directly or indirectly, even if I had a complete record of my borrowings.
(A) is not (B) would not be
Which choice do you think is correct?
Comments  
When you see:

even if I had
this is hypothetical/unreal and you should know which to choose.
Study your conditionals here:
http://www.englishpage.com/conditional/conditionalintro.html
as you should not have questions about the real/unreal issues.
There is not enough space to mention all the scholars of the last hundred years or so on whose work I have drawn directly or indirectly, even if I had a complete record of my borrowings. (Quoted from Practical English Usage, Third Edition, by Michael Swan, page vi)
Students: We have free audio pronunciation exercises.
Teo, Are you playing "Gotcha"?
If you already know the answer, why ask?
CJ
The reason for Swan choosing "is not" is "I have drawn", he sees:
There is not enough space to mention all the scholars on whose work I have drawn directly or indirectly.
as an independent sentence written in indicative, with
even if I had a complete record of my borrowings
as an afterthought, which doesn't force a subjunctive mood/conditional in it.
I ask because I don't know whether Swan is right or not. According to what I know about English grammar, he is wrong. But he is a well-educated native speaker, so I want to make sure if his sentence is grammatical.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Heck, Swan is a professor ... he knows what he's talking about ...