Inversion in conditionals

Rules

• Rule 1: Should + subject + base form (type 1)

  Replace If + present simple with Should + subject + base form. It makes the situation sound a little less likely. The main clause has will, an imperative or please.

  Pattern: Should + subject + base form, … will / imperative

  Example: Should the bell ring early, finish your sentence and pack up.

  Example: Should you find my wallet, I will give you a reward.

• Rule 2: Were + subject … (type 2)

  Replace If + past simple with Were + subject. With be: Were I rich …. With other verbs: Were + subject + to + verb. The main clause has would + verb.

  Pattern: Were + subject + adjective / noun · Were + subject + to + verb, … would + verb

  Example: Were the library bigger, we could hold the book fair there.

  Example: Were our class to win the prize, we would spend it on a trip.

• Rule 3: Had + subject + V3 (type 3)

  Replace If + had + V3 with Had + subject + V3. The main clause has would have + V3 (or would + verb in a mixed conditional).

  Pattern: Had + subject + V3, … would have + V3

  Example: Had we checked the weather, we wouldn't have gone sailing.

  Example: Had the inventor given up, we wouldn't have this machine today.

• Rule 4: Negatives – not after the subject

  No contractions in inverted conditionals. not goes after the subject: Had I not …, Should you not …. Fixed phrases: Were it not for + noun (present) and Had it not been for + noun (past).

  Pattern: Had / Should / Were + subject + not … · Were it not for / Had it not been for + noun

  Example: Had she not warned us, we would have taken the wrong path.

  Example: Had it not been for our guide, we would never have found the waterfall.

Common mistakes

• Hadn't I seen it, I wouldn't have believed it. → Had I not seen it, I wouldn't have believed it.

  No contraction; not after the subject.

• If had I known, I would have come. → Had I known, I would have come.

  Drop if completely.

• Were I win the science prize, I would buy a telescope. → Were I to win the science prize, I would buy a telescope.

  Were + subject + to + verb.