Which preposition to use with unclear

as Occurrences 1%

But if he, because of sin, shall hide himself, and not let out these beams of light, whereby we might discover light, we shall but darken counsel with words without our knowledge, and leave the matter as unclear as ever.

for Occurrences 1%

[Transcriber's note: print unclear for words in square brackets, therefore words are assumed.]

in Occurrences 1%

It was doubtless the general understanding that "revision" in this promise meant revision downward, tho this was left somewhat unclear in a campaign wherein the tariff played a somewhat minor part.

Which preposition to use with  unclear