This question already has an answer here:
"The fact of its being so rare a flower ought to have made it easier to trace the source of this particular specimen, but in practice it was an impossible task."
I just found this sentence reading a book and it sounds weird to me. I understand the meaning, but I've never seen or studied this structure in English before. I did some research on the Internet but I could find nothing. Could anyone explain the grammar? Could you please provide more examples with the same structure?