Complete the sentence with the correct form of the verb in brackets: Our roof faces north, and orientation is the only requirement we fail: we have firmly promised the housing cooperative that panels go up on any south-facing roof of ours. If ours faced south, we ___ solar panels. (install)
Correct answer
would install
Explanation
Would install states the definite unreal consequence: the standing promise leaves orientation as the only unmet requirement, so a south-facing roof would trigger the installation. Could install would state a mere possibility, weaker than the promise the premise establishes.