回看 Had I known 金案例，用 20 个全新真实现场训练 if-less conditional inversion：Had + subject 回看未实现的过去条件；Were + subject / Were + subject + to-infinitive 架设较正式的假设。材料跨生活、农业、工程、医疗、科研、审计、公共治理、法律与文化，并与问句、Never 类倒装及 Should 条件 sibling 守住边界。