Para tornar uma frase condicional formal, omita if na oração condicional, começando a frase da seguinte forma:
 
AUXILIARY VERB + SUBJECT + ( MAIN VERB ) + ...
 
Repare que o verbo auxiliar vem antes do sujeito.

 

  1   Conditional (Type 1):
  • Should you need anything, do not hesitate to ask.
    (=If you should need ...)
  • Se precisar de alguma coisa, não hesite em pedir.
     
  • Should you be late for the meeting, please give me a call.
    (=If you should be ...)
  • Se chegar atrasado à reunião, telefone-me por favor.

 

  2   Conditional (Type 2):
  • Were you to interview him, what would you ask?
    (=If you were to interview ...)
  • Se o fosse entrevistar, o que lhe perguntaria?
     
  • Were you at home right now, what would you be doing?
    (=If you were ...)
  • Se estivesse em casa agora mesmo, o que estaria a fazer?

 

  3   Conditional (Type 3):
  • Had he studied, he would have passed the exam.
    (=If he had studied ...)
  • Se ele tivesse estudado, teria passado no exame.
     
  • Had he told us he was coming, we would have waited for him.
    (=If he had told ...)
  • Se ele nos tivesse dito que vinha, teríamos esperado por ele.