Which preposition to use with questionable

in Occurrences 8%

For the bigots had begun to find something very questionable in mixing up so much love with war.

to Occurrences 6%

But SIGERSON is not content to render the neighborhood of Iron Works questionable to the delicate and apprehensive; in "shirt-factory air" he declares, upon honor, "there are little filaments of linen and cotton, with minute eggs" (goodness gracious!)

as Occurrences 2%

The notion too, which this author and others have entertained of the figure itself, is in many respects erroneous; and nearly all their examples for its illustration are either questionable as to such an application, or obviously inappropriate.

about Occurrences 1%

"My dear Mary, do you thinkleaving my rectitude asidethat I'd have referred you to Rodney Aldrich if I'd felt that there was anything questionable about it?"

at Occurrences 1%

It even seems questionable at the present moment whether we can always reckon on the support of the members of the Triple Alliance in a defensive war.

with Occurrences 1%

As the sailing directions were for every craft to fall in with the island rather to windward of the Peak, on account of the very current just mentioned, it was questionable with Mark and Betts whether any in the canoes could now perceive the boat, on account of the intervening heights.

Which preposition to use with  questionable