English, conditional protases [ read "antecedents" ] bear a close resemblance to interrogative clauses. For example, they are often identical to subordinate closed interrogative clauses:

• If Bertha accepted that offer, she's crazy.
• I don't know if Bertha accepted that offer.

They can be identical to main clause interrogatives:

• Should you see Bob?

• Should you see Bob, tell him to phone me.

• Had she asked them?

• Had she asked them, they'd have been happy to give her the elephant.

They can be very similar to and sometimes the same as main clause or subordinate clause open interrogatives:

• Whoever would agree to that?
• Whoever would agree to that, Bob won't.

Are there any non-European or non-Indo-European languages that use conditional protases that correspond to any or all of the three types of interrogative clauses listed above? I'm extremely interested in all three, but extra-specially interested in protases corresponding to closed interrogatives.