English, conditional protases [ read "antecedents" ] bear a close relationship 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 and sometimes the same as main 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 main clause open interrogatives.