were, had, should を前に出してifを省略
If I were you, I would go with her.
= If Were I you, I would go with her.
(もしわたしがあなたなら、わたしは彼女と一緒に行くのに)
I would escape soon if there should be an accident.
= I would escape soon if should there be an accident.
(万一事件があれば、わたしはすぐに逃げるだろう)
not は後ろに残る (Hadn’t×)
If I had not met her, I would not be here now.
= If Had I not met her, I would not be here now.
(もしわたしが彼女に出会っていなかったら、わたしは今ここにいないだろう)
倒置でifが不要になる理由
If you should miss the last train, ~ (万一君が終電を逃せば)
倒置 → “Should you miss the last train, ~”
“Should you miss the last train, ~”
⇒終電を逃すだろうか？ それならば~
疑問文の語順になることで、「~だろうか？それならば」というニュアンスになる。
→ ifが不要になる