5.Omission of IF

If can be omitted and the auxiliary verb moved in front of the subject (inversion). This structure is formal.

• should suggests that the condition is unlikely

       e.g.: Should you ever find yourself in Oxford, we would be glad to see you. (If you should ever find yourself in Oxford, we would be glad to see you.)

• were suggests that the condition is unlikely

      e.g.: Were the company to collapse, many people would lose their savings. (If the company collapsed, many people would lose their savings.)

• had

      e.g.: Had I known earlier that you wanted to join the team, I'd have put your name on the list. (If I had known that you wanted to join the team, I'd have put your name on the list.)