Conditional structures found in literature and formal archaic usage
Q1. ___ I but known of your distress, I would have helped
HAD I KNOWN is poetically inverted. Knowledge was lacking. Help was not given. Regrets are literary.
Q2. ___ you require assistance, do not hesitate to ask
SHOULD you is formal and courteous. Assistance is offered. Hesitation is discouraged. Politeness prevails.
Q3. ___ she my daughter, I would advise her differently
WERE SHE is subjunctive inversion. Advice is contemplated. Relationships are hypothetical. Wisdom is offered.
Q4. If I ___ a rich man, I would build a big tall house
WERE expresses counterfactual. Fiddler on the Roof quotable. Dreams are musical. Poverty is contextual.
Q5. Why are these forms considered archaic?
Archaic forms persist in literature. Modern speech simplifies. Formality recedes. Language evolves.